DSP-11 dual-specificity phosphatase

ABSTRACT

Compositions and methods are provided for the treatment of conditions associated with cell proliferation, cell differentiation and cell survival. In particular, the dual-specificity phosphatase DSP-11, and polypeptide variants thereof that stimulate dephosphorylation of DSP-11 substrates, are provided. The polypeptides may be used, for example, to identify antibodies and other agents that inhibit DSP-11 activity. The polypeptides and agents may be used to modulate cell proliferation, differentiation and survival.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.09/619,380 filed Jul. 19, 2000, now U.S. Pat. No. 6,649,391, whichapplication claims the benefit of U.S. Ser. No. 60/144,557, filed Jul.20, 1999, which are incorperated herein by reference in theirentireities

TECHNICAL FIELD

The present invention relates generally to compositions and methodsuseful for treating conditions associated with defects in cellproliferation, cell differentiation and/or cell survival. The inventionis more particularly related to dual-specificity protein phosphatases,and polypeptide variants thereof. The present invention is also relatedto the use of such polypeptides to identify antibodies and other agents,including small molecules, that modulate signal transduction leading toproliferative responses, cell differentiation and/or cell survival.

BACKGROUND OF THE INVENTION

Mitogen-activated protein kinases (MAP-kinases) are present ascomponents of conserved cellular signal transduction pathways that havea variety of conserved members. MAP-kinases are activated byphosphorylation at a dual phosphorylation motif with the sequenceThr-X-Tyr (by MAP-kinase kinases), in which phosphorylation at thetyrosine and threonine residues is required for activity. ActivatedMAP-kinases phosphorylate several transduction targets, includingtranscription factors. Inactivation of MAP-kinases is mediated bydephosphorylation at this site by dual-specificity phosphatases referredto as MAP-kinase phosphatases. In higher eukaryotes, the physiologicalrole of MAP-kinase signaling has been correlated with cellular eventssuch as proliferation, oncogenesis, development and differentiation.Accordingly, the ability to regulate signal transduction via thesepathways could lead to the development of treatments and preventivetherapies for human diseases associated with MAP-kinase signaling, suchas cancer.

Dual-specificity protein tyrosine phosphatases (dual-specificityphosphatases) are phosphatases that dephosphorylate both phosphotyrosineand phosphothreonine/serine residues (Walton et al., Ann. Rev. Biochem.62:101-120, 1993). Several dual-specificity phosphatases that inactivatea MAP-kinase have been identified, including MKP-1 (WO 97/00315; Keyseand Emslie, Nature 59:644-647, 1992), MKP-4, MKP-5, MKP-7, Hb5 (WO97/06245), PAC1 (Ward et al., Nature 367:651-654, 1994), HVH2 (Guan andButch, J. Biol. Chem. 270:7197-7203, 1995), PYST1 (Groom et al., EMBO J.15:3621-3632, 1996) and others (see, e.g., WO 95/21923). Expression ofcertain dual-specificity phosphatases is induced by stress or mitogens,but others appear to be expressed constitutively in specific cell types.The regulation of dual-specificity phosphatase expression and activityis critical for control of MAP-kinase mediated cellular functions,including cell proliferation, cell differentiation and cell survival.For example, dual-specificity phosphatases may function as negativeregulators of cell proliferation. It is likely that there are many suchdual-specificity phosphatases, with varying specificity with regard tocell type or activation. However, the regulation of dual specificityphosphatases remains poorly understood and only a relatively smallnumber of dual-specificity phosphatases have been identified.

Accordingly, there is a need in the art for an improved understanding ofMAP-kinase signaling, and the regulation of dual-specificityphosphatases within MAP-kinase signaling cascades. An increasedunderstanding of dual-specificity phosphatase regulation may facilitatethe development of methods for modulating the activity of proteinsinvolved in MAP-kinase cascades, and for treating conditions associatedwith such cascades. The present invention fulfills these needs andfurther provides other related advantages.

SUMMARY OF THE INVENTION

Briefly stated, the present invention provides compositions and methodsfor identifying agents capable of modulating cellular proliferativeresponses. In one aspect, the present invention provides isolated DSP-11polypeptides having the sequence of DSP-11 recited in SEQ ID NO:2, or avariant thereof that differs in one or more amino acid deletions,additions, insertions or substitutions at no more than 50% of theresidues in SEQ ID NO:2, such that the polypeptide retains the abilityto dephosphorylate an activated MAP-kinase.

Within further aspects, the present invention provides an isolatedpolynucleotide that encodes at least ten consecutive amino acids of apolypeptide having a sequence corresponding to SEQ ID NO:2. In certainembodiments the invention provides an isolated polynucleotide thatencodes at least fifteen consecutive amino acids of a polypeptide havinga sequence corresponding to SEQ ID NO:2. Certain such polynucleotidesencode a DSP-11 polypeptide. Still further, polynucleotides may beantisense polynucleotides that comprise at least 15 consecutivenucleotides complementary to a portion of a DSP-11 polynucleotide and/orthat detectably hybridize to the complement of the sequence recited inSEQ ID NO:1 under conditions that include a wash in 0.1×SSC and 0.1% SDSat 50° C. for 15 minutes. Also provided are expression vectorscomprising any of the foregoing polynucleotides, and host cellstransformed or transfected with such expression vectors.

The present invention further provides, within other aspects, methodsfor producing a DSP-11 polypeptide, comprising the steps of: (a)culturing a host cell as described above under conditions that permitexpression of the DSP-11 polypeptide; and (b) isolating DSP-11polypeptide from the host cell culture.

Also provided by the present invention are isolated antibodies, andantigen binding fragments thereof, that specifically bind to a DSP-11polypeptide such as a polypeptide having the sequence of SEQ ID NO:2.

The present invention further provides, within other aspects,pharmaceutical compositions comprising a polypeptide, polynucleotide,antibody or fragment thereof as described above in combination with aphysiologically acceptable carrier.

Within further aspects, the present invention provides methods fordetecting DSP-11 expression in a sample, comprising: (a) contacting asample with an antibody or an antigen-binding fragment thereof asdescribed above, under conditions and for a time sufficient to allowformation of an antibody/DSP-11 complex; and (b) detecting the level ofantibody/DSP-11 complex.

Within still other aspects, the present invention provides methods fordetecting DSP-11 expression in a sample, comprising: (a) contacting asample with an antisense polynucleotide as described above; and (b)detecting in the sample an amount of DSP-11 polynucleotide thathybridizes to the antisense polynucleotide. The amount of DSP-11polynucleotide that hybridizes to the antisense polynucleotide may bedetermined, for example, using polymerase chain reaction or ahybridization assay.

The invention also provides DSP-11 polypeptides useful in screeningassays for modulators of enzyme activity and/or substrate binding.Methods are also provided, within other aspects, for screening for anagent that modulates DSP-11 activity, comprising the steps of: (a)contacting a candidate agent with a DSP-11 polypeptide as describedabove, under conditions and for a time sufficient to permit interactionbetween the polypeptide and candidate agent; and (b) subsequentlyevaluating the ability of the polypeptide to dephosphorylate a DSP-11substrate, relative to a predetermined ability of the polypeptide todephosphorylate the DSP-11 substrate in the absence of candidate agent.Such methods may be performed in vitro or in a cellular environment(e.g., within an intact cell).

Within further aspects, methods are provided for screening for an agentthat modulates DSP-11 activity, comprising the steps of: (a) contactinga candidate agent with a cell comprising a DSP-11 promoter operablylinked to a polynucleotide encoding a detectable transcript or protein,under conditions and for a time sufficient to permit interaction betweenthe promoter and candidate agent; and (b) subsequently evaluating theexpression of the polynucleotide, relative to a predetermined level ofexpression in the absence of candidate agent.

Also provided are methods for modulating a proliferative response in acell, comprising contacting a cell with an agent that modulates DSP-11activity.

Within further aspects, methods are provided for modulatingdifferentiation of a cell, comprising contacting a cell with an agentthat modulates DSP-11 activity.

The present invention further provides methods for modulating cellsurvival, comprising contacting a cell with an agent that modulatesDSP-11 activity.

Within related aspects, the present invention provides methods fortreating a patient afflicted with a disorder associated with DSP-11activity (or treatable by administration of DSP-11), comprisingadministering to a patient a therapeutically effective amount of anagent that modulates DSP-11 activity. Such disorders include Duchennemuscular dystrophy, cancer, graft-versus-host disease, autoimmunediseases, allergies, metabolic diseases, abnormal cell growth, abnormalcell proliferation and cell cycle abnormalities.

Within further aspects, DSP-11 substrate trapping mutant polypeptidesare provided. Such polypeptides differ from the sequence recited in SEQID NO:2 in one or more amino acid deletions, additions, insertions orsubstitutions at no more than 50% of the residues in SEQ ID NO:2, suchthat the polypeptide binds to a substrate with an affinity that is notsubstantially diminished relative to DSP-11, and such that the abilityof the polypeptide to dephosphorylate a substrate is reduced relative toDSP-11. Within certain specific embodiments, a substrate trapping mutantpolypeptide contains a substitution at position 65 or position 95 of SEQID NO:2.

The present invention further provides, within other aspects, methodsfor screening a molecule for the ability to interact with DSP-11,comprising the steps of: (a) contacting a candidate molecule with apolypeptide as described above under conditions and for a timesufficient to permit the candidate molecule and polypeptide to interact;and (b) detecting the presence or absence of binding of the candidatemolecule to the polypeptide. The step of detecting may comprise, forexample, an affinity purification step, a yeast two hybrid screen or ascreen of a phage display library.

These and other aspects of the present invention will become apparentupon reference to the following detailed description and attacheddrawings. All references disclosed herein are hereby incorporated byreference in their entirety as if each was incorporated individually.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents a cDNA sequence for DSP-11 (SEQ ID NO:1), with the startand stop codons indicated in bold.

FIG. 2 presents the predicted amino acid sequence of DSP-11 (SEQ IDNO:2).

FIG. 3 is a sequence alignment showing sequence similarity betweenDSP-11 and other MAP-kinase phosphatases (SEQ ID NOS: 14-22).

FIG. 4 shows northern blot hybridization using a ³²P-labeled full lengthDSP-11 encoding nucleic acid sequence as probe. Blot contained humanpolyA+ RNA from various tissue types as follows: He, heart; Br, brain;Pl, placenta; Lu, lung; Li, liver; SM, skeletal muscle; Ki, kidney; Pa,pancreas.

FIG. 5 presents cDNA coding sequence for a murine DSP-11 variant (SEQ IDNO:12).

FIG. 6 presents the predicted amino acid sequence of a murine DSP-11variant (SEQ ID NO:13).

DETAILED DESCRIPTION OF THE INVENTION

As noted above, the present invention is generally directed tocompositions and methods for modulating (i.e., stimulating orinhibiting) cellular proliferative responses, in vitro and in vivo. Inparticular, the present invention provides a dual-specificityphosphatase DSP-11 (FIGS. 1-2; SEQ ID NOs:1-2), as well as variantsthereof and antibodies that specifically bind DSP-11. Also providedherein are methods for using such compounds for screens, detectionassays and related therapeutic uses.

DSP-11 POLYPEPTIDES AND POLYNUCLEOTIDES

As used herein, the term “DSP-11 polypeptide” refers to a polypeptidethat comprises a DSP-11 sequence as provided herein or a variant of sucha sequence. Such polypeptides are capable of dephosphorylating bothtyrosine and threonine/serine residues in a DSP-11 substrate, with anactivity that is not substantially diminished relative to that of a fulllength native DSP-11. DSP-11 substrates include activated (i.e.,phosphorylated) MAP-kinases. Other substrates may be identified usingsubstrate trapping mutants, as described herein, and includepolypeptides having one or more phosphorylated tyrosine, threonineand/or serine residues.

DSP-11 polypeptide variants within the scope of the present inventionmay contain one or more substitutions, deletions, additions and/orinsertions. For certain DSP-11 variants, the ability of the variant todephosphorylate tyrosine and threonine residues within a DSP-11substrate is not substantially diminished. The ability of such a DSP-11variant to dephosphorylate tyrosine and threonine residues within aDSP-11 substrate may be enhanced or unchanged, relative to a nativeDSP-11, or may be diminished by less than 50%, and preferably less than20%, relative to native DSP-11. Such variants may be identified usingthe representative assays provided herein.

Also contemplated by the present invention are modified forms of DSP-11in which a specific function is disabled. For example, such proteins maybe constitutively active or inactive, or may display altered binding orcatalytic properties. Such altered proteins may be generated using wellknown techniques, and the altered function confirmed using screens suchas those provided herein. Certain modified DSP-11 polypeptides are knownas “substrate trapping mutants.” Such polypeptides retain the ability tobind a substrate (i.e., K_(m) is not substantially diminished), butdisplay a reduced ability to dephosphorylate a substrate (i.e., k_(cat)is reduced, preferably to less than 1 per minute). Further, thestability of the substrate trapping mutant/substrate complex should notbe substantially diminished, relative to the stability of aDSP-11/substrate complex. Complex stability may be assessed based on theassociation constant (K_(a)). Determination of K_(m), k_(cat) and K_(a)may be readily accomplished using standard techniques known in the art(see, e.g., WO 98/04712; Lehninger, Biochemistry, 1975 Worth Publishers,NY) and assays provided herein. Substrate trapping mutants may begenerated, for example, by modifying DSP-11 with an amino acidsubstitution at position 65 or position 95 (e.g., by replacing the aminoacid aspartate at position 65 with an alanine residue, or by replacingthe cysteine at residue 95 with a serine). Substrate trapping mutantsmay be used, for example, to identify DSP-11 substrates. Briefly, themodified DSP-11 may be contacted with a candidate substrate (alone orwithin a mixture of proteins, such as a cell extract) to permit theformation of a substrate/DSP-11 complex. The complex may then beisolated by conventional techniques to permit the isolation andcharacterization of substrate. The preparation and use of substratetrapping mutants is described, for example, within PCT Publication No.WO 98/04712.

Preferably, a variant contains conservative substitutions. A“conservative substitution” is one in which an amino acid is substitutedfor another amino acid that has similar properties, such that oneskilled in the art of peptide chemistry would expect the secondarystructure and hydropathic nature of the polypeptide to be substantiallyunchanged. Amino acid substitutions may generally be made on the basisof similarity in polarity, charge, solubility, hydrophobicity,hydrophilicity and/or the amphipathic nature of the residues. Forexample, negatively charged amino acids include aspartic acid andglutamic acid; positively charged amino acids include lysine andarginine; and amino acids with uncharged polar head groups havingsimilar hydrophilicity values include leucine, isoleucine and valine;glycine and alanine; asparagine and glutamine; and serine, threonine,phenylalanine and tyrosine. Other groups of amino acids that mayrepresent conservative changes include: (1) ala, pro, gly, glu, asp,gln, asn, ser, thr; (2) cys, ser, tyr, thr; (3) val, ile, leu, met, ala,phe; (4) lys, arg, his; and (5) phe, tyr, trp, his. A variant may also,or alternatively, contain nonconservative changes.

In general, modifications may be more readily made in non-criticalregions, which are regions of the native sequence that do notsubstantially change the activity of DSP-11. Non-critical regions may beidentified by modifying the DSP-11 sequence in a particular region andassaying the ability of the resulting variant in a phosphatase assay, asdescribed herein. Preferred sequence modifications are made so as toretain the active site domain (VGVHCALGFGRTGTMLACYLV; SEQ ID NO:3).Within certain preferred embodiments, such modifications affectinteractions between DSP-11 and cellular components other than DSP-11substrates. However, substitutions may also be made in critical regionsof the native protein, provided that the resulting variant substantiallyretains the ability to stimulate substrate dephosphorylation. Withincertain embodiments, a variant contains substitutions, deletions,additions and/or insertions at no more than 50%, preferably no more than25%, of the amino acid residues.

Variants may also (or alternatively) be modified by, for example, thedeletion or addition of amino acids that have minimal influence on theactivity of the polypeptide. In particular, variants may containadditional amino acid sequences at the amino and/or carboxy termini.Such sequences may be used, for example, to facilitate purification ordetection of the polypeptide.

DSP-11 polypeptides may be prepared using any of a variety of well knowntechniques. Recombinant polypeptides encoded by DNA sequences asdescribed below may be readily prepared from the DNA sequences using anyof a variety of expression vectors known to those having ordinary skillin the art. Expression may be achieved in any appropriate host cell thathas been transformed or transfected with an expression vector containinga DNA molecule that encodes a recombinant polypeptide. Suitable hostcells include prokaryotes, yeast and higher eukaryotic cells (includingmammalian cells), and forms that differ in glycosylation may begenerated by varying the host cell or post-isolation processing.Supernatants from suitable host/vector systems which secrete recombinantprotein or polypeptide into culture media may be first concentratedusing a commercially available filter. Following concentration, theconcentrate may be applied to a suitable purification matrix such as anaffinity matrix or an ion exchange resin. Finally, one or more reversephase HPLC steps can be employed to further purify a recombinantpolypeptide.

Portions and other variants having fewer than about 100 amino acids, andgenerally fewer than about 50 amino acids, may also be generated bysynthetic procedures, using techniques well known to those havingordinary skill in the art. For example, such polypeptides may besynthesized using any of the commercially available solid-phasetechniques, such as the Merrifield solid-phase synthesis method, whereamino acids are sequentially added to a growing amino acid chain. SeeMerrifield, J. Am. Chem. Soc. 85:2149-2146, 1963. Equipment forautomated synthesis of polypeptides is commercially available fromsuppliers such as Perkin-Elmer, Inc., Applied BioSystems Division(Foster City, Calif.), and may be operated according to themanufacturer's instructions.

A “DSP-11 polynucleotide” is any polynucleotide that encodes at least aportion of a DSP-11 polypeptide or a variant thereof, or that iscomplementary to such a polynucleotide. Preferred polynucleotidescomprise at least 15 consecutive nucleotides, preferably at least 30consecutive nucleotides, that encode a DSP-11 polypeptide or that arecomplementary to such a sequence. Certain polynucleotides encode aDSP-11 polypeptide; others may find use as probes, primers or antisenseoligonucleotides, as described below. Polynucleotides may besingle-stranded (coding or antisense) or double-stranded, and may be DNA(genomic, cDNA or synthetic) or RNA molecules. Additional coding ornon-coding sequences may, but need not, be present within apolynucleotide of the present invention, and a polynucleotide may, butneed not, be linked to other molecules and/or support materials.

DSP-11 polynucleotides may comprise a native sequence (i.e., anendogenous DSP-11 sequence or a portion or splice variant thereof) ormay comprise a variant of such a sequence. Polynucleotide variants maycontain one or more substitutions, additions, deletions and/orinsertions such that the activity of the encoded polypeptide is notsubstantially diminished, as described above. The effect on the activityof the encoded polypeptide may generally be assessed as describedherein. Variants preferably exhibit at least about 70% identity, morepreferably at least about 80% identity and most preferably at leastabout 90% identity to a polynucleotide sequence that encodes a nativeDSP-11 or a portion thereof. The percent identity may be readilydetermined by comparing sequences using computer algorithms well knownto those having ordinary skill in the art, such as Align or the BLASTalgorithm (Altschul, J. Mol. Biol. 219:555-565, 1991; Henikoff andHenikoff, Proc. Natl. Acad. Sci. USA 89:10915-10919, 1992), which isavailable at the NCBI website(http://www/ncbi.nlm.nih.gov/cgi-bin/BLAST). Default parameters may beused. Certain variants are substantially homologous to a native gene.Such polynucleotide variants are capable of hybridizing under moderatelystringent conditions to a naturally occurring DNA or RNA sequenceencoding a native DSP-11 (or a complementary sequence). Suitablemoderately stringent conditions include, for example, prewashing in asolution of 5×SSC, 0.5% SDS, 1.0 mM EDTA (pH 8.0); hybridizing at 50°C.-70° C., 5×SSC for 1-16 hours; followed by washing once or twice at22-65° C. for 20-40 minutes with one or more each of 2×, 0.5× and0.2×SSC containing 0.05-0.1% SDS. For additional stringency, conditionsmay include a wash in 0.1×SSC and 0.1% SDS at 50-60° C. for 15-40minutes. As known to those having ordinary skill in the art, variationsin stringency of hybridization conditions may be achieved by alteringthe time, temperature and/or concentration of the solutions used forprehybridization, hybridization and wash steps, and suitable conditionsmay also depend in part on the particular nucleotide sequences of theprobe used, and of the blotted, proband nucleic acid sample.Accordingly, it will be appreciated that suitably stringent conditionscan be readily selected without undue experimentation where a desiredselectivity of the probe is identified, based on its ability tohybridize to one or more certain proband sequences while not hybridizingto certain other proband sequences.

It will also be appreciated by those having ordinary skill in the artthat, as a result of the degeneracy of the genetic code, there are manynucleotide sequences that encode a polypeptide as described herein. Someof these polynucleotides bear minimal homology to the nucleotidesequence of any native gene. Nonetheless, polynucleotides that vary dueto differences in codon usage are specifically contemplated by thepresent invention.

Polynucleotides may be prepared using any of a variety of techniques.For example, a polynucleotide may be amplified from cDNA prepared from asuitable cell or tissue type, such as human brain, testis, kidney orskeletal muscle. Such polynucleotides may be amplified via polymerasechain reaction (PCR). For this approach, sequence-specific primers maybe designed based on the sequences provided herein, and may be purchasedor synthesized.

An amplified portion may be used to isolate a full length gene from asuitable library (e.g., human brain, testis, kidney, liver or skeletalmuscle cDNA) using well known techniques. Within such techniques, alibrary (cDNA or genomic) is screened using one or more polynucleotideprobes or primers suitable for amplification. Preferably, a library issize-selected to include larger molecules. Random primed libraries mayalso be preferred for identifying 5′ and upstream regions of genes.Genomic libraries are preferred for obtaining introns and extending 5′sequences.

For hybridization techniques, a partial sequence may be labeled (e.g.,by nick-translation or end-labeling with ³²P) using well knowntechniques. A bacterial or bacteriophage library may then be screened byhybridizing filters containing denatured bacterial colonies (or lawnscontaining phage plaques) with the labeled probe (see e.g., Sambrook etal., Molecular Cloning: A Laboratory Manual, Cold Spring HarborLaboratories, Cold Spring Harbor, N.Y., 1989). Hybridizing colonies orplaques are selected and expanded, and the DNA is isolated for furtheranalysis. Clones may be analyzed to determine the amount of additionalsequence by, for example, PCR using a primer from the partial sequenceand a primer from the vector. Restriction maps and partial sequences maybe generated to identify one or more overlapping clones. A full lengthcDNA molecule can be generated by ligating suitable fragments, usingwell known techniques.

Alternatively, there are numerous amplification techniques for obtaininga full length coding sequence from a partial cDNA sequence. Within suchtechniques, amplification is generally performed via PCR. One suchtechnique is known as “rapid amplification of cDNA ends” or RACE. Thistechnique involves the use of an internal primer and an external primer,which hybridizes to a polyA region or vector sequence, to identifysequences that are 5′ and 3′ of a known sequence. Any of a variety ofcommercially available kits may be used to perform the amplificationstep. Primers may be designed using, for example, software well known inthe art. Primers are preferably 17-32 nucleotides in length, have a GCcontent of at least 40% and anneal to the target sequence attemperatures of about 54° C. to 72° C. The amplified region may besequenced as described above, and overlapping sequences assembled into acontiguous sequence.

A cDNA sequence encoding DSP-11 is provided in FIG. 1 (SEQ ID NO:1), andthe predicted amino acid sequence is provided in FIG. 2 (SEQ ID NO:2).The DSP-11 active site (VGVHCALGFGRTGTMLACYLV; SEQ ID NO:3), is locatedat positions 91 through 110 of SEQ ID NO:2. Sequence informationimmediately adjacent to this site was used to design 5′ and 3′ RACEreactions with human kidney cDNA to identify a 450 base pair cDNA thatcorresponds to a mRNA that displays a higher abundance in kidney andliver RNA. This cDNA encodes a protein of 150 amino acids that isreferred to herein as dual specificity phosphatase-11, or DSP-11. DSP-11shows significant homology to other MAP-kinase phosphatases, as shown bythe sequence comparison presented in FIG. 3.

DSP-11 polynucleotide variants may generally be prepared by any methodknown in the art, including, for example, solid phase chemicalsynthesis. Modifications in a polynucleotide sequence may also beintroduced using standard mutagenesis techniques, such asoligonucleotide-directed site-specific mutagenesis. Alternatively, RNAmolecules may be generated by in vitro or in vivo transcription of DNAsequences encoding DSP-11, or a portion thereof, provided that the DNAis incorporated into a vector with a suitable RNA polymerase promoter(such as T7 or SP6). Certain polynucleotides may be used to prepare anencoded polypeptide, as described herein. In addition, or alternatively,a polynucleotide may be administered to a patient such that the encodedpolypeptide is generated in vivo.

A polynucleotide that is complementary to at least a portion of a codingsequence (e.g., an antisense polynucleotide or a ribozyme) may also beused as a probe or primer, or to modulate gene expression.Identification of oligonucleotides and ribozymes for use as antisenseagents, and DNA encoding genes for their targeted delivery, involvemethods well known in the art. For example, the desirable properties,lengths and other characteristics of such oligonucleotides are wellknown. Antisense oligonucleotides are typically designed to resistdegradation by endogenous nucleolytic enzymes by using such linkages as:phosphorothioate, methylphosphonate, sulfone, sulfate, ketyl,phosphorodithioate, phosphoramidate, phosphate esters, and other suchlinkages (see, e.g., Agrwal et al., Tetrahedron Lett. 28:3539-3542(1987); Miller et al., J. Am. Chem. Soc. 93:6657-6665 (1971); Stec etal., Tetrahedron Lett. 26:2191-2194 (1985); Moody et al., Nucl. AcidsRes. 12:4769-4782 (1989); Uznanski et al., Nucl. Acids Res. (1989);Letsinger et al., Tetrahedron 40:137-143 (1984); Eckstein, Annu. Rev.Biochem. 54:367-402 (1985); Eckstein, Trends Biol. Sci. 14:97-100(1989); Stein In: Oligodeoxynucleotides. Antisense Inhibitors of GeneExpression, Cohen, Ed, Macmillan Press, London, pp. 97-117 (1989); Jageret al., Biochemistry 27:7237-7246 (1988)).

Antisense polynucleotides are oligonucleotides that bind in asequence-specific manner to nucleic acids, such as mRNA or DNA. Whenbound to mRNA that has complementary sequences, antisense preventstranslation of the mRNA (see, e.g., U.S. Pat. No. 5,168,053 to Altman etal.; U.S. Pat. No. 5,190,931 to Inouye, U.S. Pat. No. 5,135,917 toBurch; U.S. Pat. No. 5,087,617 to Smith and Clusel et al. (1993) Nucl.Acids Res. 21:3405-3411, which describes dumbbell antisenseoligonucleotides). Triplex molecules refer to single DNA strands thatbind duplex DNA forming a colinear triplex molecule, thereby preventingtranscription (see, e.g., U.S. Pat. No. 5,176,996 to Hogan et al., whichdescribes methods for making synthetic oligonucleotides that bind totarget sites on duplex DNA).

Particularly useful antisense nucleotides and triplex molecules aremolecules that are complementary to or bind the sense strand of DNA ormRNA that encodes a DSP-11 polypeptide or a protein mediating any otherprocess related to expression of endogenous DSP-11, such that inhibitionof translation of mRNA encoding the DSP-11 polypeptide is effected. cDNAconstructs that can be transcribed into antisense RNA may also beintroduced into cells or tissues to facilitate the production ofantisense RNA. Antisense technology can be used to control geneexpression through interference with binding of polymerases,transcription factors or other regulatory molecules (see Gee et al., InHuber and Carr, Molecular and Immunologic Approaches, Futura PublishingCo. (Mt. Kisco, N.Y.; 1994)). Alternatively, an antisense molecule maybe designed to hybridize with a control region of a DSP-11 gene (e.g.,promoter, enhancer or transcription initiation site), and blocktranscription of the gene; or to block translation by inhibiting bindingof a transcript to ribosomes.

The present invention also contemplates DSP-11-specific ribozymes. Aribozyme is an RNA molecule that specifically cleaves RNA substrates,such as mRNA, resulting in specific inhibition or interference withcellular gene expression. There are at least five known classes ofribozymes involved in the cleavage and/or ligation of RNA chains.Ribozymes can be targeted to any RNA transcript and can catalyticallycleave such transcripts (see, e.g., U.S. Pat. No. 5,272,262; U.S. Pat.No. 5,144,019; and U.S. Pat. Nos. 5,168,053, 5,180,818, 5,116,742 and5,093,246 to Cech et al.). Any DSP-11 mRNA-specific ribozyme, or anucleic acid encoding such a ribozyme, may be delivered to a host cellto effect inhibition of DSP-11 gene expression. Ribozymes may thereforebe delivered to the host cells by DNA encoding the ribozyme linked to aeukaryotic promoter, such as a eukaryotic viral promoter, such that uponintroduction into the nucleus, the ribozyme will be directlytranscribed.

Any polynucleotide may be further modified to increase stability invivo. Possible modifications include, but are not limited to, theaddition of flanking sequences at the 5′ and/or 3′ ends; the use ofphosphorothioate or 2′ O-methyl rather than phosphodiester linkages inthe backbone; and/or the inclusion of nontraditional bases such asinosine, queosine and wybutosine, as well as acetyl-methyl-, thio- andother modified forms of adenine, cytidine, guanine, thymine and uridine.

Nucleotide sequences as described herein may be joined to a variety ofother nucleotide sequences using established recombinant DNA techniques.For example, a polynucleotide may be cloned into any of a variety ofcloning vectors, including plasmids, phagemids, lambda phage derivativesand cosmids. Vectors of particular interest include expression vectors,replication vectors, probe generation vectors and sequencing vectors. Ingeneral, a suitable vector contains an origin of replication functionalin at least one organism, convenient restriction endonuclease sites andone or more selectable markers. Other elements will depend upon thedesired use, and will be apparent to those having ordinary skill in theart.

Within certain embodiments, polynucleotides may be formulated so as topermit entry into a cell of a mammal, and expression therein. Suchformulations are particularly useful for therapeutic purposes, asdescribed below. Those having ordinary skill in the art will appreciatethat there are many ways to achieve expression of a polynucleotide in atarget cell, and any suitable method may be employed. For example, apolynucleotide may be incorporated into a viral vector using well knowntechniques. A viral vector may additionally transfer or incorporate agene for a selectable marker (to aid in the identification or selectionof transduced cells) and/or a targeting moiety, such as a gene thatencodes a ligand for a receptor on a specific target cell, to render thevector target specific. Targeting may also be accomplished using anantibody, by methods known to those having ordinary skill in the art.

Other formulations for therapeutic purposes include colloidal dispersionsystems, such as macromolecule complexes, nanocapsules, microspheres,beads, and lipid-based systems including oil-in-water emulsions,micelles, mixed micelles, and liposomes. A preferred colloidal systemfor use as a delivery vehicle in vitro and in vivo is a liposome (i.e.,an artificial membrane vesicle). The preparation and use of such systemsis well known in the art.

Within other aspects, a DSP-11 promoter may be isolated using standardtechniques. The present invention provides nucleic acid moleculescomprising such a promoter or one or more cis- or trans-actingregulatory elements thereof. Such regulatory elements may enhance orsuppress expression of DSP-11. A 5′ flanking region may be generatedusing standard techniques, based on the genomic sequence providedherein. If necessary, additional 5′ sequences may be generated usingPCR-based or other standard methods. The 5′ region may be subcloned andsequenced using standard methods. Primer extension and/or RNaseprotection analyses may be used to verify the transcriptional start sitededuced from the cDNA.

To define the boundary of the promoter region, putative promoter insertsof varying sizes may be subcloned into a heterologous expression systemcontaining a suitable reporter gene without a promoter or enhancer.Suitable reporter genes may include genes encoding luciferase,beta-galactosidase, chloramphenicol acetyl transferase, secretedalkaline phosphatase or the Green Fluorescent Protein gene. Suitableexpression systems are well known and may be prepared using well knowntechniques or obtained commercially. Internal deletion constructs may begenerated using unique internal restriction sites or by partialdigestion of non-unique restriction sites. Constructs may then betransfected into cells that display high levels of DSP-11 expression. Ingeneral, the construct with the minimal 5′ flanking region showing thehighest level of expression of reporter gene is identified as thepromoter. Such promoter regions may be linked to a reporter gene andused to evaluate agents for the ability to modulate DSP-11transcription.

Once a functional promoter is identified, cis- and trans-acting elementsmay be located. Cis-acting sequences may generally be identified basedon homology to previously characterized transcriptional motifs. Pointmutations may then be generated within the identified sequences toevaluate the regulatory role of such sequences. Such mutations may begenerated using site-specific mutagenesis techniques or a PCR-basedstrategy. The altered promoter is then cloned into a reporter geneexpression vector, as described above, and the effect of the mutation onreporter gene expression is evaluated.

The present invention also contemplates the use of allelic variants ofDSP-11, as well as DSP-11 sequences from other organisms. Such sequencesmay generally be identified based upon similarity to the sequencesprovided herein (e.g., using hybridization techniques) and based uponthe presence of DSP-11 activity, using an assay provided herein.

In general, polypeptides and polynucleotides as described herein areisolated. An “isolated” polypeptide or polynucleotide is one that isremoved from its original environment. For example, anaturally-occurring protein is isolated if it is separated from some orall of the coexisting materials in the natural system. Preferably, suchpolypeptides are at least about 90% pure, more preferably at least about95% pure and most preferably at least about 99% pure. A polynucleotideis considered to be isolated if, for example, it is cloned into a vectorthat is not a part of the natural environment.

ASSAYS FOR DETECTING DSP-11 ACTIVITY

According to the present invention, substrates of DSP-11 may includefull length tyrosine phosphorylated proteins and polypeptides as well asfragments (e.g., portions), derivatives or analogs thereof that can bephosphorylated at a tyrosine residue and that may, in certain preferredembodiments, also be able to undergo phosphorylation at a serine or athreonine residue. Such fragments, derivatives and analogs include anynaturally occurring or artificially engineered DSP-11 substratepolypeptide that retains at least the biological function of interactingwith a DSP-11 as provided herein, for example by forming a complex witha DSP-11. A fragment, derivative or analog of a DSP-11 substratepolypeptide, including substrates that are fusion proteins, may be (i)one in which one or more of the amino acid residues are substituted witha conserved or non-conserved amino acid residue (preferably a conservedamino acid residue), and such substituted amino acid residue may or maynot be one encoded by the genetic code, or (ii) one in which one or moreof the amino acid residues includes a substituent group, or (iii) one inwhich the substrate polypeptide is fused with another compound, such asa compound to increase the half-life of the polypeptide (e.g.,polyethylene glycol) or a detectable moiety such as a reporter molecule,or (iv) one in which additional amino acids are fused to the substratepolypeptide, including amino acids that are employed for purification ofthe substrate polypeptide or a proprotein sequence. Such fragments,derivatives and analogs are deemed to be within the scope of thoseskilled in the art. In preferred embodiment, a MAP-kinase polypeptide isa substrate for use as provided herein.

DSP-11 polypeptide variants may be tested for DSP-11 activity using anysuitable assay for MAP-kinase phosphatase activity. Such assays may beperformed in vitro or within a cell-based assay. For example, aMAP-kinase may be obtained in inactive form from Upstate Biotechnology(Lake Placid, N.Y.; catalog number 14-198), for use as a DSP-11substrate as provided herein. Phosphorylation of the MAP-kinase can beperformed using well known techniques (such as those described by Zhengand Guan, J. Biol. Chem. 268:16116-16119, 1993) using the MAP-kinasekinase MEK-1 (available from Upstate Biotechnology; cat. no. 14-206).

For example, [³²P]-radiolabeled substrate (e.g., MAP-kinase) may be usedfor the kinase reaction, resulting in radiolabeled, activatedMAP-kinase. A DSP-11 polypeptide may then be tested for the ability todephosphorylate an activated MAP-kinase by contacting the DSP-11polypeptide with the MAP-kinase under suitable conditions (e.g., Tris,pH 7.5, 1 mM EDTA, 1 mM dithiothreitol, 1 mg/mL bovine serum albumin for10 minutes at 30° C.; or as described by Zheng and Guan, J. Biol. Chem.268:16116-16119, 1993). Dephosphorylation of the MAP-kinase may bedetected using any of a variety of assays, such as a coupled kinaseassay (evaluating phosphorylation of a MAP-kinase substrate using anyassay generally known in the art) or directly, based on (1) the loss ofradioactive phosphate groups. (e.g., by gel electrophoresis, followed byautoradiography); (2) the shift in electrophoretic mobility followingdephosphorylation; (3) the loss of reactivity with an antibody specificfor phosphotyrosine or phosphothreonine; or (4) a phosphoamino acidanalysis of the MAP-kinase. Certain assays may generally be performed asdescribed by Ward et al., Nature 367:651-654, 1994 or Alessi et al.,Oncogene 8:2015-2020, 1993. In general, contact of 500 pg-50 ng ofDSP-11 polypeptide with 100 ng-100 μg activated MAP-kinase should resultin a detectable dephosphorylation of the MAP-kinase, typically within20-30 minutes. Within certain embodiments, 0.01-10 units/mL (preferablyabout 0.1 units/mL, where a unit is an amount sufficient todephosphorylate 1 nmol substrate per minute) DSP-11 polypeptide may becontacted with 0.1-10 μM (preferably about 1 μM) activated MAP-kinase toproduce a detectable dephosphorylation of a MAP-kinase. Preferably, aDSP-11 polypeptide results in a dephosphorylation of a MAP-kinase or aphosphorylated substrate (such as a tyrosine and/orserine-phosphorylated peptide) that is at least as great as thedephosphorylation observed in the presence of a comparable amount ofnative human DSP-11. It will be apparent that other substratesidentified using a substrate trapping mutant as described herein may besubstituted for the MAP-kinase within such assays.

ANTIBODIES AND ANTIGEN-BINDING FRAGMENTS

Also contemplated by the present invention are peptides, polypeptides,and other non-peptide molecules that specifically bind to a DSP-11. Asused herein, a molecule is said to “specifically bind” to a DSP-11 if itreacts at a detectable level with DSP-11, but does not react detectablywith peptides containing an unrelated sequence, or a sequence of adifferent phosphatase. Preferred binding molecules include antibodies,which may be, for example, polyclonal, monoclonal, single chain,chimeric, anti-idiotypic, or CDR-grafted immunoglobulins, or fragmentsthereof, such as proteolytically generated or recombinantly producedimmunoglobulin F(ab′)₂, Fab, Fv, and Fd fragments. Certain preferredantibodies are those antibodies that inhibit or block DSP-11 activitywithin an in vitro assay, as described herein. Binding properties of anantibody to DSP-11 may generally be assessed using immunodetectionmethods including, for example, an enzyme-linked immunosorbent assay(ELISA), immunoprecipitation, immunoblotting and the like, which may bereadily performed by those having ordinary skill in the art.

Methods well known in the art may be used to generate antibodies,polyclonal antisera or monoclonal antibodies that are specific for aDSP-11. Antibodies also may be produced as genetically engineeredimmunoglobulins (Ig) or Ig fragments designed to have desirableproperties. For example, by way of illustration and not limitation,antibodies may include a recombinant IgG that is a chimeric fusionprotein having at least one variable (V) region domain from a firstmammalian species and at least one constant region domain from a second,distinct mammalian species. Most commonly, a chimeric antibody hasmurine variable region sequences and human constant region sequences.Such a murine/human chimeric immunoglobulin may be “humanized” bygrafting the complementarity determining regions (CDRs) derived from amurine antibody, which confer binding specificity for an antigen, intohuman-derived V region framework regions and human-derived constantregions. Fragments of these molecules may be generated by proteolyticdigestion, or optionally, by proteolytic digestion followed by mildreduction of disulfide bonds and alkylation. Alternatively, suchfragments may also be generated by recombinant genetic engineeringtechniques.

As used herein, an antibody is said to be “immunospecific” or to“specifically bind” a DSP-11 polypeptide if it reacts at a detectablelevel with DSP-11, preferably with an affinity constant, K_(a), ofgreater than or equal to about 10⁴ M⁻¹, more preferably of greater thanor equal to about 10⁵ M⁻¹, more preferably of greater than or equal toabout 10⁶ M⁻¹, and still more preferably of greater than or equal toabout 10⁷ M⁻¹. Affinities of binding partners or antibodies can bereadily determined using conventional techniques, for example, thosedescribed by Scatchard et al. (Ann. N.Y. Acad. Sci. USA 51:660 (1949))or by surface plasmon resonance (BIAcore, Biosensor, Piscataway, N.J.).See, e.g., Wolff et al., Cancer Res. 53:2560-2565 (1993).

Antibodies may generally be prepared by any of a variety of techniquesknown to those having ordinary skill in the art. See, e.g., Harlow etal., Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory(1988). In one such technique, an animal is immunized with DSP-11 as anantigen to generate polyclonal antisera. Suitable animals include, forexample, rabbits, sheep, goats, pigs, cattle, and may also includesmaller mammalian species, such as mice, rats, and hamsters, or otherspecies.

An immunogen may be comprised of cells expressing DSP-11, purified orpartially purified DSP-11 polypeptides or variants or fragments (e.g.,peptides) thereof, or DSP-11 peptides. DSP-11 peptides may be generatedby proteolytic cleavage or may be chemically synthesized. For instance,nucleic acid sequences encoding DSP-11 polypeptides are provided herein,such that those skilled in the art may routinely prepare thesepolypeptides for use as immunogens. Polypeptides or peptides useful forimmunization may also be selected by analyzing the primary, secondary,and tertiary structure of DSP-11 according to methods known to thoseskilled in the art, in order to determine amino acid sequences morelikely to generate an antigenic response in a host animal. See, e.g.,Novotny, 1991 Mol. Immunol. 28:201-207; Berzofsky, 1985 Science229:932-40.

Preparation of the immunogen for injection into animals may includecovalent coupling of the DSP-11 polypeptide (or variant or fragmentthereof), to another immunogenic protein, for example, a carrier proteinsuch as keyhole limpet hemocyanin (KLH) or bovine serum albumin (BSA).In addition, the DSP-11 peptide, polypeptide, or DSP-11-expressing cellsto be used as immunogen may be emulsified in an adjuvant. See, e.g.,Harlow et al., Antibodies: A Laboratory Manual, Cold Spring HarborLaboratory (1988). In general, after the first injection, animalsreceive one or more booster immunizations according to a preferredschedule that may vary according to, inter alia, the antigen, theadjuvant (if any) and/or the particular animal species. The immuneresponse may be monitored by periodically bleeding the animal,separating the sera out of the collected blood, and analyzing the serain an immunoassay, such as an ELISA or Ouchterlony diffusion assay, orthe like, to determine the specific antibody titer. Once an antibodytiter is established, the animals may be bled periodically to accumulatethe polyclonal antisera. Polyclonal antibodies that bind specifically tothe DSP-11 polypeptide or peptide may then be purified from suchantisera, for example, by affinity chromatography using protein A, orthe DSP-11 polypeptide, immobilized on a suitable solid support.

Monoclonal antibodies that specifically bind to DSP-11 polypeptides orfragments or variants thereof, and hybridomas, which are immortaleukaryotic cell lines, that produce monoclonal antibodies having thedesired binding specificity, may also be prepared, for example, usingthe technique of Kohler and Milstein (Nature, 256:495-497; 1976, Eur. JImmunol. 6:511-519 (1975)) and improvements thereto. An animal—forexample, a rat, hamster, or preferably mouse-is immunized with a DSP-11immunogen prepared as described above. Lymphoid cells that includeantibody-forming cells, typically spleen cells, are obtained from animmunized animal and may be immortalized by fusion with adrug-sensitized myeloma (e.g., plasmacytoma) cell fusion partner,preferably one that is syngeneic with the immunized animal and thatoptionally has other desirable properties (e.g., inability to expressendogenous Ig gene products). The lymphoid (e.g., spleen) cells and themyeloma cells may be combined for a few minutes with a membranefusion-promoting agent, such as polyethylene glycol or a nonionicdetergent, and then plated at low density on a selective medium thatsupports the growth of hybridoma cells, but not unfused myeloma cells. Apreferred selection media is HAT (hypoxanthine, aminopterin, thymidine).After a sufficient time, usually about one to two weeks, colonies ofcells are observed. Single colonies are isolated, and antibodiesproduced by the cells may be tested for binding activity to the DSP-11polypeptide, or variant or fragment thereof. Hybridomas producingmonoclonal antibodies with high affinity and specificity for a DSP-11antigen are preferred. Hybridomas that produce monoclonal antibodiesthat specifically bind to a DSP-11 polypeptide or variant or fragmentthereof are therefore contemplated by the present invention.

Monoclonal antibodies may be isolated from the supernatants of hybridomacultures. An alternative method for production of a murine monoclonalantibody is to inject the hybridoma cells into the peritoneal cavity ofa syngeneic mouse, for example, a mouse that has been treated (e.g.,pristane-primed) to promote formation of ascites fluid containing themonoclonal antibody. Contaminants may be removed from the subsequently(usually within 1-3 weeks) harvested ascites fluid by conventionaltechniques, such as chromatography, gel filtration, precipitation,extraction, or the like. For example, antibodies may be purified byaffinity chromatography using an appropriate ligand selected based onparticular properties of the monoclonal antibody (e.g., heavy or lightchain isotype, binding specificity, etc.). Examples of a suitableligand, immobilized on a solid support, include Protein A, Protein G, ananti-constant region (light chain or heavy chain) antibody, ananti-idiotype antibody and a DSP-11 polypeptide or fragment or variantthereof.

Human monoclonal antibodies may be generated by any number of techniqueswith which those having ordinary skill in the art will be familiar. Suchmethods include but are not limited to, Epstein Barr Virus (EBV)transformation of human peripheral blood cells (e.g., containing Blymphocytes), in vitro immunization of human B cells, fusion of spleencells from immunized transgenic mice carrying human immunoglobulin genesinserted by yeast artificial chromosomes (YAC), isolation from humanimmunoglobulin V region phage libraries, or other procedures as known inthe art and based on the disclosure herein.

For example, one method for generating human monoclonal antibodiesincludes immortalizing human peripheral blood cells by EBVtransformation. See, e.g., U.S. Pat. No. 4,464,456. An immortalized cellline producing a monoclonal antibody that specifically binds to a DSP-11polypeptide (or a variant or fragment thereof) can be identified byimmunodetection methods as provided herein, for example, an ELISA, andthen isolated by standard cloning techniques. Another method to generatehuman monoclonal antibodies, in vitro immunization, includes priminghuman splenic B cells with antigen, followed by fusion of primed B cellswith a heterohybrid fusion partner. See, e.g., Boerner et al., 1991 J.Immunol. 147:86-95.

Still another method for the generation of human DSP-11-specificmonoclonal antibodies and polyclonal antisera for use in the presentinvention relates to transgenic mice. See, e.g., U.S. Pat. No.5,877,397; Bruggemann et al., 1997 Curr. Opin. Biotechnol. 8:455-58;Jakobovits et al., 1995 Ann. N.Y. Acad. Sci. 764:525-35. In these mice,human immunoglobulin heavy and light chain genes have been artificiallyintroduced by genetic engineering in germline configuration, and theendogenous murine immunoglobulin genes have been inactivated. See, e.g.,Bruggemann et al., 1997 Curr. Opin. Biotechnol. 8:455-58. For example,human immunoglobulin transgenes may be mini-gene constructs, ortransloci on yeast artificial chromosomes, which undergo B cell-specificDNA rearrangement and hypermutation in the mouse lymphoid tissue. See,Bruggemann et al., 1997 Curr. Opin. Biotechnol. 8:455-58. Humanmonoclonal antibodies specifically binding to DSP-11 may be obtained byimmunizing the transgenic animals, fusing spleen cells with myelomacells, selecting and then cloning cells producing antibody, as describedabove. Polyclonal sera containing human antibodies may also be obtainedfrom the blood of the immunized animals.

Chimeric antibodies, specific for a DSP-11, including humanizedantibodies, may also be generated according to the present invention. Achimeric antibody has at least one constant region domain derived from afirst mammalian species and at least one variable region domain derivedfrom a second, distinct mammalian species. See, e.g., Morrison et al.,1984, Proc. Natl. Acad. Sci. USA, 81:6851-55. In preferred embodiments,a chimeric antibody may be constructed by cloning the polynucleotidesequence that encodes at least one variable region domain derived from anon-human monoclonal antibody, such as the variable region derived froma murine, rat, or hamster monoclonal antibody, into a vector containinga nucleic acid sequence that encodes at least one human constant region.See, e.g., Shin et al., 1989 Methods Enzymol. 178:459-76; Walls et al.,1993 Nucleic Acids Res. 21:2921-29. By way of example, thepolynucleotide sequence encoding the light chain variable region of amurine monoclonal antibody may be inserted into a vector containing anucleic acid sequence encoding the human kappa light chain constantregion sequence. In a separate vector, the polynucleotide sequenceencoding the heavy chain variable region of the monoclonal antibody maybe cloned in frame with sequences encoding the human IgG1 constantregion. The particular human constant region selected may depend uponthe effector functions desired for the particular antibody (e.g.,complement fixing, binding to a particular Fc receptor, etc.). Anothermethod known in the art for generating chimeric antibodies is homologousrecombination (e.g., U.S. Pat. No. 5,482,856). Preferably, the vectorswill be transfected into eukaryotic cells for stable expression of thechimeric antibody.

A non-human/human chimeric antibody may be further geneticallyengineered to create a “humanized” antibody. Such a humanized antibodymay comprise a plurality of CDRs derived from an immunoglobulin of anon-human mammalian species, at least one human variable frameworkregion, and at least one human immunoglobulin constant region.Humanization may in certain embodiments provide an antibody that hasdecreased binding affinity for a DSP-11 when compared, for example, witheither a non-human monoclonal antibody from which a DSP-11 bindingvariable region is obtained, or a chimeric antibody having such a Vregion and at least one human C region, as described above. Usefulstrategies for designing humanized antibodies may therefore include, forexample by way of illustration and not limitation, identification ofhuman variable framework regions that are most homologous to thenon-human framework regions of the chimeric antibody. Without wishing tobe bound by theory, such a strategy may increase the likelihood that thehumanized antibody will retain specific binding affinity for a DSP-11,which in some preferred embodiments may be substantially the sameaffinity for a DSP-11 polypeptide or variant or fragment thereof, and incertain other preferred embodiments may be a greater affinity forDSP-11. See, e.g., Jones et al., 1986 Nature 321:522-25; Riechmann etal., 1988 Nature 332:323-27. Designing such a humanized antibody maytherefore include determining CDR loop conformations and structuraldeterminants of the non-human variable regions, for example, by computermodeling, and then comparing the CDR loops and determinants to knownhuman CDR loop structures and determinants. See, e.g., Padlan et al.,1995 FASEB 9:133-39; Chothia et al., 1989 Nature, 342:377-383. Computermodeling may also be used to compare human structural templates selectedby sequence homology with the non-human variable regions. See, e.g.,Bajorath et al., 1995 Ther. Immunol. 2:95-103; EP-0578515-A3. Ifhumanization of the non-human CDRs results in a decrease in bindingaffinity, computer modeling may aid in identifying specific amino acidresidues that could be changed by site-directed or other mutagenesistechniques to partially, completely or supra-optimally (i.e., increaseto a level greater than that of the non-humanized antibody) restoreaffinity. Those having ordinary skill in the art are familiar with thesetechniques, and will readily appreciate numerous variations andmodifications to such design strategies.

Within certain embodiments, the use of antigen-binding fragments ofantibodies may be preferred. Such fragments include Fab fragments orF(ab′)₂ fragments, which may be prepared by proteolytic digestion withpapain or pepsin, respectively. The antigen binding fragments may beseparated from the Fc fragments by affinity chromatography, for example,using immobilized protein A or protein G, or immobilized DSP-11polypeptide, or a suitable variant or fragment thereof. Those havingordinary skill in the art can routinely and without undueexperimentation determine what is a suitable variant or fragment basedon characterization of affinity purified antibodies obtained, forexample, using immunodetection methods as provided herein. Analternative method to generate Fab fragments includes mild reduction ofF(ab′)₂ fragments followed by alkylation. See, e.g., Weir, Handbook ofExperimental Immunology, 1986, Blackwell Scientific, Boston.

According to certain embodiments, non-human, human, or humanized heavychain and light chain variable regions of any of the above described Igmolecules may be constructed as single chain Fv (sFv) polypeptidefragments (single chain antibodies). See, e.g., Bird et al., 1988Science 242:423-426; Huston et al., 1988 Proc. Natl. Acad. Sci. USA85:5879-5883. Multi-functional sFv fusion proteins may be generated bylinking a polynucleotide sequence encoding an sFv polypeptide in-framewith at least one polynucleotide sequence encoding any of a variety ofknown effector proteins. These methods are known in the art, and aredisclosed, for example, in EP-B1-0318554, U.S. Pat. No. 5,132,405, U.S.Pat. No. 5,091,513, and U.S. Pat. No. 5,476,786. By way of example,effector proteins may include immunoglobulin constant region sequences.See, e.g., Hollenbaugh et al., 1995 J. Immunol. Methods 188:1-7. Otherexamples of effector proteins are enzymes. As a non-limiting example,such an enzyme may provide a biological activity for therapeuticpurposes (see, e.g., Siemers et al., 1997 Bioconjug. Chem. 8:510-19), ormay provide a detectable activity, such as horseradishperoxidase-catalyzed conversion of any of a number of well-knownsubstrates into a detectable product, for diagnostic uses. Still otherexamples of sFv fusion proteins include Ig-toxin fusions, orimmunotoxins, wherein the sFv polypeptide is linked to a toxin. Thosehaving ordinary skill in the art will appreciate that a wide variety ofpolypeptide sequences have been identified that, under appropriateconditions, are toxic to cells. As used herein, a toxin polypeptide forinclusion in an immunoglobulin-toxin fusion protein may be anypolypeptide capable of being introduced to a cell in a manner thatcompromises cell survival, for example, by directly interfering with avital function or by inducing apoptosis. Toxins thus may include, forexample, ribosome-inactivating proteins, such as Pseudomonas aeruginosaexotoxin A, plant gelonin, bryodin from Bryonia dioica, or the like.See, e.g., Thrush et al., 1996 Annu. Rev. Immunol. 14:49-71; Frankel etal., 1996 Cancer Res. 56:926-32. Numerous other toxins, includingchemotherapeutic agents, anti-mitotic agents, antibiotics, inducers ofapoptosis (or “apoptogens”, see, e.g., Green and Reed, 1998, Science281:1309-1312), or the like, are known to those familiar with the art,and the examples provided herein are intended to be illustrative withoutlimiting the scope and spirit of the invention.

The sFv may, in certain embodiments, be fused to peptide or polypeptidedomains that permit detection of specific binding between the fusionprotein and antigen (e.g., a DSP-11). For example, the fusionpolypeptide domain may be an affinity tag polypeptide. Binding of thesFv fusion protein to a binding partner (e.g., a DSP-11) may thereforebe detected using an affinity polypeptide or peptide tag, such as anavidin, streptavidin or a His (e.g., polyhistidine) tag, by any of avariety of techniques with which those skilled in the art will befamiliar. Detection techniques may also include, for example, binding ofan avidin or streptavidin fusion protein to biotin or to a biotinmimetic sequence (see, e.g., Luo et al., 1998 J. Biotechnol. 65:225 andreferences cited therein), direct covalent modification of a fusionprotein with a detectable moiety (e.g., a labeling moiety), non-covalentbinding of the fusion protein to a specific labeled reporter molecule,enzymatic modification of a detectable substrate by a fusion proteinthat includes a portion having enzyme activity, or immobilization(covalent or non-covalent) of the fusion protein on a solid-phasesupport.

The sFv fusion protein of the present invention, comprising aDSP-11-specific immunoglobulin-derived polypeptide fused to anotherpolypeptide such as an effector peptide having desirable affinityproperties, may therefore include, for example, a fusion protein whereinthe effector peptide is an enzyme such as glutathione-S-transferase. Asanother example, sFv fusion proteins may also comprise a DSP-11-specificIg polypeptide fused to a Staphylococcus aureus protein A polypeptide;protein A encoding nucleic acids and their use in constructing fusionproteins having affinity for immunoglobulin constant regions aredisclosed generally, for example, in U.S. Pat. No. 5,100,788. Otheruseful affinity polypeptides for construction of sFv fusion proteins mayinclude streptavidin fusion proteins, as disclosed, for example, in WO89/03422; U.S. Pat. No. 5,489,528; U.S. Pat. No. 5,672,691; WO 93/24631;U.S. Pat. No. 5,168,049; U.S. Pat. No. 5,272,254 and elsewhere, andavidin fusion proteins (see, e.g., EP 511,747). As provided herein, sFvpolypeptide sequences may be fused to fusion polypeptide sequences,including effector protein sequences, that may include full lengthfusion polypeptides and that may alternatively contain variants orfragments thereof.

An additional method for selecting antibodies that specifically bind toa DSP-11 polypeptide or variant or fragment thereof is by phage display.See, e.g., Winter et al., 1994 Annul. Rev. Immunol. 12:433-55; Burton etal., 1994 Adv. Immunol. 57:191-280. Human or murine immunoglobulinvariable region gene combinatorial libraries may be created in phagevectors that can be screened to select Ig fragments (Fab, Fv, sFv, ormultimers thereof) that bind specifically to a DSP-11 polypeptide orvariant or fragment thereof. See, e.g, U.S. Pat. No. 5,223,409; Huse etal., 1989 Science 246:1275-81; Kang et al., 1991 Proc. Natl. Acad. Sci.USA 88:4363-66; Hoogenboom et al., 1992 J. Molec. Biol. 227:381-388;Schlebusch et al., 1997 Hybridoma 16:47-52 and references cited therein.For example, a library containing a plurality of polynucleotidesequences encoding Ig variable region fragments may be inserted into thegenome of a filamentous bacteriophage, such as M13 or a variant thereof,in frame with the sequence encoding a phage coat protein, for instance,gene III or gene VIII of M13, to create an M13 fusion protein. A fusionprotein may be a fusion of the coat protein with the light chainvariable region domain and/or with the heavy chain variable regiondomain.

According to certain embodiments, immunoglobulin Fab fragments may alsobe displayed on the phage particle, as follows. Polynucleotide sequencesencoding Ig constant region domains may be inserted into the phagegenome in frame with a coat protein. The phage coat fusion protein maythus be fused to an Ig light chain or heavy chain fragment (Fd). Forexample, from a human Ig library, the polynucleotide sequence encodingthe human kappa constant region may be inserted into a vector in framewith the sequence encoding at least one of the phage coat proteins.Additionally or alternatively, the polynucleotide sequence encoding thehuman IgG1 CH1 domain may be inserted in frame with the sequenceencoding at least one other of the phage coat proteins. A plurality ofpolynucleotide sequences encoding variable region domains (e.g., derivedfrom a DNA library) may then be inserted into the vector in frame withthe constant region-coat protein fusions, for expression of Fabfragments fused to a bacteriophage coat protein.

Phage that display an Ig fragment (e.g., an Ig V-region or Fab) thatbinds to a DSP-11 polypeptide may be selected by mixing the phagelibrary with DSP-11 or a variant or a fragment thereof, or by contactingthe phage library with a DSP-11 polypeptide immobilized on a solidmatrix under conditions and for a time sufficient to allow binding.Unbound phage are removed by a wash, which typically may be a buffercontaining salt (e.g., NaCl) at a low concentration, preferably withless than 100 mM NaCl, more preferably with less than 50 mM NaCl, mostpreferably with less than 10 mM NaCl, or, alternatively, a buffercontaining no salt. Specifically bound phage are then eluted with anNaCl-containing buffer, for example, by increasing the saltconcentration in a step-wise manner. Typically, phage that bind theDSP-11 with higher affinity will require higher salt concentrations tobe released. Eluted phage may be propagated in an appropriate bacterialhost, and generally, successive rounds of DSP-11 binding and elution canbe repeated to increase the yield of phage expressing DSP-11 specificimmunoglobulin. Combinatorial phage libraries may also be used forhumanization of non-human variable regions. See, e.g., Rosok et al.,1996 J. Biol. Chem. 271:22611-18; Rader et al., 1998 Proc. Natl. Acad.Sci. USA 95:8910-15. The DNA sequence of the inserted immunoglobulingene in the phage so selected may be determined by standard techniques.See, Sambrook et al., 1989 Molecular Cloning: A Laboratory Manual, ColdSpring Harbor Press. The affinity selected Ig-encoding sequence may thenbe cloned into another suitable vector for expression of the Ig fragmentor, optionally, may be cloned into a vector containing Ig constantregions, for expression of whole immunoglobulin chains.

Phage display techniques may also be used to select polypeptides,peptides or single chain antibodies that bind to DSP-11. For examples ofsuitable vectors having multicloning sites into which candidate nucleicacid molecules (e.g., DNA) encoding such peptides or antibodies may beinserted, see, e.g., McLafferty et al., Gene 128:29-36, 1993; Scott etal., 1990 Science 249:386-390; Smith et al., 1993 Methods Enzymol.217:228-257; Fisch et al., 1996, Proc. Natl. Acad. Sci. USA 93:7761-66.The inserted DNA molecules may comprise randomly generated sequences, ormay encode variants of a known peptide or polypeptide domain thatspecifically binds to a DSP-11 polypeptide, or variant or fragmentthereof, as provided herein. Generally, the nucleic acid insert encodesa peptide of up to 60 amino acids, more preferably a peptide of 3 to 35amino acids, and still more preferably a peptide of 6 to 20 amino acids.The peptide encoded by the inserted sequence is displayed on the surfaceof the bacteriophage. Phage expressing a binding domain for a DSP-11polypeptide may be selected on the basis of specific binding to animmobilized DSP-11 polypeptide as described above. As provided herein,well-known recombinant genetic techniques may be used to constructfusion proteins containing the fragment thereof. For example, apolypeptide may be generated that comprises a tandem array of two ormore similar or dissimilar affinity selected DSP-11 binding peptidedomains, in order to maximize binding affinity for DSP-11 of theresulting product.

In certain other embodiments, the invention contemplates DSP-11 specificantibodies that are multimeric antibody fragments. Useful methodologiesare described generally, for example in Hayden et al. 1997, Curr Opin.Immunol. 9:201-12; Coloma et al., 1997 Nat. Biotechnol. 15:159-63). Forexample, multimeric antibody fragments may be created by phagetechniques to form miniantibodies (U.S. Pat. No. 5,910,573) or diabodies(Holliger et al., 1997, Cancer Immunol. Immunother. 45:128-130).Multimeric fragments may be generated that are multimers of aDSP-11-specific Fv, or that are bispecific antibodies comprising aDSP-11-specific Fv noncovalently associated with a second Fv having adifferent antigen specificity. See, e.g., Koelemij et al., 1999 J.Immunother. 22:514-24. As another example, a multimeric antibody maycomprise a bispecific antibody having two single chain antibodies or Fabfragments. According to certain related embodiments, a first Ig fragmentmay be specific for a first antigenic determinant on a DSP-11polypeptide (or variant or fragment thereof), while a second Ig fragmentmay be specific for a second antigenic determinant of the DSP-11polypeptide. Alternatively, in certain other related embodiments, afirst immunoglobulin fragment may be specific for an antigenicdeterminant on a DSP-11 polypeptide or variant or fragment thereof, anda second immunoglobulin fragment may be specific for an antigenicdeterminant on a second, distinct (i.e., non-DSP-11) molecule. Alsocontemplated are bispecific antibodies that specifically bind DSP-11,wherein at least one antigen-binding domain is present as a fusionprotein.

Introducing amino acid mutations into DSP-11-binding immunoglobulinmolecules may be useful to increase the specificity or affinity forDSP-11, or to alter an effector function. Immunoglobulins with higheraffinity for DSP-11 may be generated by site-directed mutagenesis ofparticular residues. Computer assisted three-dimensional molecularmodeling may be employed to identify the amino acid residues to bechanged, in order to improve affinity for the DSP-11 polypeptide. See,e.g., Mountain et al., 1992, Biotechnol. Genet. Eng. Rev. 10: 1-142.Alternatively, combinatorial libraries of CDRs may be generated in M13phage and screened for immunoglobulin fragments with improved affinity.See, e.g., Glaser et al., 1992, J. Immunol. 149:3903-3913; Barbas etal., 1994 Proc. Natl. Acad. Sci. USA 91:3809-13; U.S. Pat. No.5,792,456).

Effector functions may also be altered by site-directed mutagenesis.See, e.g., Duncan et al., 1988 Nature 332:563-64; Morgan et al., 1995Immunology 86:319-24; Eghtedarzedeh-Kondri et al., 1997 Biotechniques23:830-34. For example, mutation of the glycosylation site on the Fcportion of the immunoglobulin may alter the ability of theimmunoglobulin to fix complement. See, e.g., Wright et al., 1997 TrendsBiotechnol. 15:26-32. Other mutations in the constant region domains mayalter the ability of the immunoglobulin to fix complement, or to effectantibody-dependent cellular cytotoxicity. See, e.g., Duncan et al., 1988Nature 332:563-64; Morgan et al., 1995 Immunology 86:319-24; Sensel etal., 1997 Mol. Immunol. 34:1019-29.

The nucleic acid molecules encoding an antibody or fragment thereof thatspecifically binds DSP-11, as described herein, may be propagated andexpressed according to any of a variety of well-known procedures fornucleic acid excision, ligation, transformation and transfection. Thus,in certain embodiments expression of an antibody fragment may bepreferred in a prokaryotic host, such as Escherichia coli (see, e.g.,Pluckthun et al., 1989 Methods Enzymol. 178:497-515). In certain otherembodiments, expression of the antibody or a fragment thereof may bepreferred in a eukaryotic host cell, including yeast (e.g.,Saccharomyces cerevisiae, Schizosaccharomyces pombe, and Pichiapastoris), animal cells (including mammalian cells) or plant cells.Examples of suitable animal cells include, but are not limited to,myeloma, COS, CHO, or hybridoma cells. Examples of plant cells includetobacco, corn, soybean, and rice cells. By methods known to those havingordinary skill in the art and based on the present disclosure, a nucleicacid vector may be designed for expressing foreign sequences in aparticular host system, and then polynucleotide sequences encoding theDSP-11 binding antibody (or fragment thereof) may be inserted. Theregulatory elements will vary according to the particular host.

A DSP-11-binding immunoglobulin (or fragment thereof) as describedherein may contain a detectable moiety or label such as an enzyme,cytotoxic agent or other reporter molecule, including a dye,radionuclide, luminescent group, fluorescent group, or biotin, or thelike. The DSP-11-specific immunoglobulin or fragment thereof may beradiolabeled for diagnostic or therapeutic applications. Techniques forradiolabeling of antibodies are known in the art. See, e.g., Adams 1998In Vivo 12:11-21; Hiltunen 1993 Acta Oncol. 32:831-9. Therapeuticapplications are described in greater detail below and may include useof the DSP-11-binding antibody (or fragment thereof) in conjunction withother therapeutic agents. The antibody or fragment may also beconjugated to a cytotoxic agent as known in the art and provided herein,for example, a toxin, such as a ribosome-inactivating protein, achemotherapeutic agent, an anti-mitotic agent, an antibiotic or thelike.

The invention also contemplates the generation of anti-idiotypeantibodies that recognize an antibody (or antigen-binding fragmentthereof) that specifically binds to DSP-11 as provided herein, or avariant or fragment thereof. Anti-idiotype antibodies may be generatedas polyclonal antibodies or as monoclonal antibodies by the methodsdescribed herein, using an anti-DSP-11 antibody (or antigen-bindingfragment thereof) as immunogen. Anti-idiotype antibodies or fragmentsthereof may also be generated by any of the recombinant geneticengineering methods described above, or by phage display selection. Ananti-idiotype antibody may react with the antigen binding site of theanti-DSP-11 antibody such that binding of the anti-DSP-11 antibody to aDSP-11 polypeptide is competitively inhibited. Alternatively, ananti-idiotype antibody as provided herein may not competitively inhibitbinding of an anti-DSP-11 antibody to a DSP-11 polypeptide.

As provided herein and according to methodologies well known in the art,polyclonal and monoclonal antibodies may be used for the affinityisolation of DSP-11 polypeptides. See, e.g., Hermanson et al.,Immobilized Affinity Ligand Techniques, Academic Press, Inc. New York,1992. Briefly, an antibody (or antigen-binding fragment thereof) may beimmobilized on a solid support material, which is then contacted with asample comprising the polypeptide of interest (e.g., a DSP-11).Following separation from the remainder of the sample, the polypeptideis then released from the immobilized antibody.

METHODS FOR DETECTING DSP-11 EXPRESSION

Certain aspects of the present invention provide methods that employantibodies raised against DSP-11, or hybridizing polynucleotides, fordiagnostic and assay purposes. Certain assays involve using an antibodyor other agent to detect the presence or absence of DSP-11, orproteolytic fragments thereof. Alternatively, nucleic acid encodingDSP-11 may be detected, using standard hybridization and/or PCRtechniques. Suitable probes and primers may be designed by those havingordinary skill in the art based on the DSP-11 cDNA sequence providedherein. Assays may generally be performed using any of a variety ofsamples obtained from a biological source, such as eukaryotic cells,bacteria, viruses, extracts prepared from such organisms and fluidsfound within living organisms. Biological samples that may be obtainedfrom a patient include blood samples, biopsy specimens, tissue explants,organ cultures and other tissue or cell preparations. A patient orbiological source may be a human or non-human animal, a primary cellculture or culture adapted cell line including but not limited togenetically engineered cell lines that may contain chromosomallyintegrated or episomal recombinant nucleic acid sequences, immortalizedor immortalizable cell lines, somatic cell hybrid cell lines,differentiated or differentiatable cell lines, transformed cell linesand the like. In certain preferred embodiments the patient or biologicalsource is a human, and in certain preferred embodiments the biologicalsource is a non-human animal that is a mammal, for example, a rodent(e.g., mouse, rat, hamster, etc.), an ungulate (e.g., bovine) or anon-human primate. In certain other preferred embodiments of theinvention, a patient may be suspected of having or being at risk forhaving a disease associated with altered cellular signal transduction,or may be known to be free of a risk for or presence of such as disease.

To detect DSP-11 protein, the reagent is typically an antibody, whichmay be prepared as described below. There are a variety of assay formatsknown to those having ordinary skill in the art for using an antibody todetect a polypeptide in a sample. See, e.g., Harlow and Lane,Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory, 1988.For example, the assay may be performed in a Western blot format,wherein a protein preparation from the biological sample is resolved bygel electrophoresis, transferred to a suitable membrane and allowed toreact with the antibody. The presence of the antibody on the membranemay then be detected using a suitable detection reagent, as describedbelow.

In another embodiment, the assay involves the use of antibodyimmobilized on a solid support to bind to the target DSP-11 and removeit from the remainder of the sample. The bound DSP-11 may then bedetected using a second antibody or reagent that contains a reportergroup. Alternatively, a competitive assay may be utilized, in which aDSP-11 polypeptide is labeled with a reporter group and allowed to bindto the immobilized antibody after incubation of the antibody with thesample. The extent to which components of the sample inhibit the bindingof the labeled polypeptide to the antibody is indicative of thereactivity of the sample with the immobilized antibody, and as a result,indicative of the level of DSP-11 in the sample.

The solid support may be any material known to those having ordinaryskill in the art to which the antibody may be attached, such as a testwell in a microtiter plate, a nitrocellulose filter or another suitablemembrane. Alternatively, the support may be a bead or disc, such asglass, fiberglass, latex or a plastic such as polystyrene orpolyvinylchloride. The antibody may be immobilized on the solid supportusing a variety of techniques known to those in the art, which are amplydescribed in the patent and scientific literature.

In certain embodiments, the assay for detection of DSP-11 in a sample isa two-antibody sandwich assay. This assay may be performed by firstcontacting an antibody that has been immobilized on a solid support,commonly the well of a microtiter plate, with the biological sample,such that DSP-11 within the sample is allowed to bind to the immobilizedantibody (a 30 minute incubation time at room temperature is generallysufficient). Unbound sample is then removed from the immobilizedDSP-11/antibody complexes and a second antibody (containing a reportergroup such as an enzyme, dye, radionuclide, luminescent group,fluorescent group or biotin) capable of binding to a different site onthe DSP-11 is added. The amount of second antibody that remains bound tothe solid support is then determined using a method appropriate for thespecific reporter group. For radioactive groups, scintillation countingor autoradiographic methods are generally appropriate. Spectroscopicmethods may be used to detect dyes, luminescent groups and fluorescentgroups. Biotin may be detected using avidin, coupled to a differentreporter group (commonly a radioactive or fluorescent group or anenzyme). Enzyme reporter groups may generally be detected by theaddition of substrate (generally for a specific period of time),followed by spectroscopic or other analysis of the reaction products.Standards and standard additions may be used to determine the level ofDSP-11 in a sample, using well known techniques.

In a related aspect of the present invention, kits for detecting DSP-11and DSP-11 phosphatase activity are provided. Such kits may be designedfor detecting the level of DSP-11 or nucleic acid encoding DSP-11, ormay detect phosphatase activity of DSP-11 in a direct phosphatase assayor a coupled phosphatase assay. In general, the kits of the presentinvention comprise one or more containers enclosing elements, such asreagents or buffers, to be used in the assay.

A kit for detecting the level of DSP-11, or nucleic acid encodingDSP-11, typically contains a reagent that binds to the DSP-11 protein,DNA or RNA. To detect nucleic acid encoding DSP-11, the reagent may be anucleic acid probe or a PCR primer. To detect DSP-11 protein, thereagent is typically an antibody. Such kits also contain a reportergroup suitable for direct or indirect detection of the reagent (i.e.,the reporter group may be covalently bound to the reagent or may bebound to a second molecule, such as Protein A, Protein G, immunoglobulinor lectin, which is itself capable of binding to the reagent). Suitablereporter groups include, but are not limited to, enzymes (e.g.,horseradish peroxidase), substrates, cofactors, inhibitors, dyes,radionuclides, luminescent groups, fluorescent groups and biotin. Suchreporter groups may be used to directly or indirectly detect binding ofthe reagent to a sample component using standard methods known to thosehaving ordinary skill in the art.

Kits for detecting DSP-11 activity typically comprise a DSP-11 substratein combination with a suitable buffer. DSP-11 activity may bespecifically detected by performing an immunoprecipitation step with aDSP-11-specific antibody prior to performing a phosphatase assay asdescribed above. Other reagents for use in detecting dephosphorylationof substrate may also be provided.

Within certain diagnostic assays, a proliferative disorder may bedetected in a patient or any other biological source organism asprovided herein based on the presence of an altered DSP-11 or an alteredlevel of DSP-11 expression. For example, an antibody may distinguishbetween a wild-type DSP-11 and an altered DSP-11 having a variation inamino acid sequence. Such a variation may be indicative of the presenceof a proliferative disorder, or of susceptibility to such a disorder.Hybridization and amplification techniques may be similarly used todetect modified DSP-11 sequences.

METHODS FOR IDENTIFYING MODULATORS OF DSP-11 ACTIVITY

In one aspect of the present invention, DSP-11 polypeptides may be usedto identify agents that modulate DSP-11 activity. Such agents mayinhibit or enhance signal transduction via a MAP-kinase cascade, leadingto cell proliferation. An agent that modulates DSP-11 activity may alterexpression and/or stability of DSP-11, DSP-11 protein activity and/orthe ability of DSP-11 to dephosphorylate a substrate. Agents that may bescreened within such assays include, but are not limited to, antibodiesand antigen-binding fragments thereof, competing substrates or peptidesthat represent, for example, a catalytic site or a dual phosphorylationmotif, antisense polynucleotides and ribozymes that interfere withtranscription and/or translation of DSP-11 and other natural andsynthetic molecules, for example small molecule inhibitors, that bind toand inactivate DSP-11.

Candidate agents for use in a method of screening for a modulator ofDSP-11 according to the present invention may be provided as “libraries”or collections of compounds, compositions or molecules. Such moleculestypically include compounds known in the art as “small molecules” andhaving molecular weights less than 10⁵ daltons, preferably less than 10⁴daltons and still more preferably less than 10³ daltons. For example,members of a library of test compounds can be administered to aplurality of samples, each containing at least one DSP-11 polypeptide asprovided herein, and then assayed for their ability to enhance orinhibit DSP-11-mediated dephosphorylation of, or binding to, asubstrate. Compounds so identified as capable of influencing DSP-11function (e.g., phosphotyrosine and/or phosphoserine/threoninedephosphorylation) are valuable for therapeutic and/or diagnosticpurposes, since they permit treatment and/or detection of diseasesassociated with DSP-11 activity. Such compounds are also valuable inresearch directed to molecular signaling mechanisms that involve DSP-11,and to refinements in the discovery and development of future DSP-11compounds exhibiting greater specificity.

Candidate agents further may be provided as members of a combinatoriallibrary, which preferably includes synthetic agents prepared accordingto a plurality of predetermined chemical reactions performed in aplurality of reaction vessels. For example, various starting compoundsmay be prepared employing one or more of solid-phase synthesis, recordedrandom mix methodologies and recorded reaction split techniques thatpermit a given constituent to traceably undergo a plurality ofpermutations and/or combinations of reaction conditions. The resultingproducts comprise a library that can be screened followed by iterativeselection and synthesis procedures, such as a synthetic combinatoriallibrary of peptides (see e.g., PCT/US91/08694, PCT/US91/04666, which arehereby incorporated by reference in their entireties) or othercompositions that may include small molecules as provided herein (seee.g., PCT/US94/08542, EP 0774464, U.S. Pat. No. 5,798,035, U.S. Pat. No.5,789,172, U.S. Pat. No. 5,751,629, which are hereby incorporated byreference in their entireties). Those having ordinary skill in the artwill appreciate that a diverse assortment of such libraries may beprepared according to established procedures, and tested using DSP-11according to the present disclosure.

In certain embodiments, modulating agents may be identified by combininga candidate agent with a DSP-11 polypeptide or a polynucleotide encodingsuch a polypeptide, in vitro or in vivo, and evaluating the effect ofthe candidate agent on the DSP-11 phosphatase activity using, forexample, a representative assay described herein. An increase ordecrease in phosphatase activity can be measured by performing arepresentative assay provided herein in the presence and absence of acandidate agent. Briefly, a candidate agent may be included in a mixtureof active DSP-11 polypeptide and substrate (e.g., a phosphorylatedMAP-kinase), with or without pre-incubation with one or more componentsof the mixture. In general, a suitable amount of antibody or other agentfor use in such an assay ranges from about 0.01 μM to about 100 μM. Theeffect of the agent on DSP-11 activity may then be evaluated byquantifying the loss of phosphate from the substrate, and comparing theloss with that achieved using DSP-11 without the addition of a candidateagent. Alternatively, a coupled kinase assay may be used, in whichDSP-11 activity is indirectly measured based on MAP-kinase activity.

Alternatively, a polynucleotide comprising a DSP-11 promoter operablylinked to a DSP-11 coding region or reporter gene may be used toevaluate the effect of a test compound on DSP-11 transcription. Suchassays may be performed in cells that express DSP-11 endogenously (e.g.,human or other mammalian kidney or liver) or in cells transfected withan expression vector comprising a DSP-11 promoter linked to a reportergene. The effect of a test compound may then be evaluated by assayingthe effect on transcription of DSP-11 or the reporter using, forexample, a Northern blot analysis or a suitable reporter activity assay.

DSP-11 activity may also be measured in whole cells transfected with areporter gene whose expression is dependent upon the activation of anappropriate substrate. For example, appropriate cells (i.e., cells thatexpress DSP-11) may be transfected with a substrate-dependent promoterlinked to a reporter gene. In such a system, expression of the reportergene (which may be readily detected using methods well known to those ofordinary skill in the art) depends upon activation of substrate.Dephosphorylation of substrate may be detected based on a decrease inreporter activity. Candidate modulating agents may be added to such asystem, as described above, to evaluate their effect on DSP-11 activity.

The present invention further provides methods for identifying amolecule that interacts with, or binds to, DSP-11. Such a moleculegenerally associates with DSP-11 with an affinity constant (K_(a)) of atleast 10⁴, preferably at least 10⁵, more preferably at least 10⁶, stillmore preferably at least 10⁷ and most preferably at least 10⁸. Affinityconstants may be determined using well known techniques. Methods foridentifying interacting molecules may be used, for example, as initialscreens for modulating agents, or to identify factors that are involvedin the in vivo DSP-11 activity. Techniques for substrate trapping, forexample using of DSP-11 variants or substrate trapping mutants asdescribed above, are also contemplated according to certain embodimentsprovided herein. In addition to standard binding assays, there are manyother techniques that are well known for identifying interactingmolecules, including yeast two-hybrid screens, phage display andaffinity techniques. Such techniques may be performed using routineprotocols, which are well known to those having ordinary skill in theart (see, e.g., Bartel et al., In Cellular Interactions in Development:A Practical Approach, D. A. Harley, ed., Oxford University Press(Oxford, UK), pp. 153-179, 1993). Within these and other techniques,candidate interacting proteins (e.g., putative DSP-11 substrates) may bephosphorylated prior to assaying for the presence of DSP-11-binding orinteracting proteins.

Within other aspects, the present invention provides animal models inwhich an animal either does not express a functional DSP-11, orexpresses an altered DSP-11. Such animals may be generated usingstandard homologous recombination strategies. Animal models generated inthis manner may be used to study activities of DSP-11 polypeptides andmodulating agents in vivo.

METHODS FOR DEPHOSPHORYLATING A SUBSTRATE

In another aspect of the present invention, a DSP-11 polypeptide may beused for dephosphorylating a substrate of DSP-11 as provided herein. Inone embodiment, a substrate may be dephosphorylated in vitro byincubating a DSP-11 polypeptide with a substrate in a suitable buffer(e.g., Tris, pH 7.5, 1 mM EDTA, 1 mM dithiothreitol, 1 mg/mL bovineserum albumin) for 10 minutes at 30° C. Any compound that can bedephosphorylated by DSP-11, such as a MAP-kinase, may be used as asubstrate. In general, the amounts of the reaction components may rangefrom about 50 pg to about 50 ng of DSP-11 polypeptide and from about 10ng to about 10 μg of substrate. Dephosphorylated substrate may then bepurified, for example, by affinity techniques and/or gelelectrophoresis. The extent of substrate dephosphorylation may generallybe monitored by adding [γ-³²P]labeled substrate to a test aliquot, andevaluating the level of substrate dephosphorylation as described herein.

METHODS FOR MODULATING CELLULAR RESPONSES

Modulating agents may be used to modulate, modify or otherwise alter(e.g., alter increase or decrease) cellular responses such as cellproliferation, differentiation and survival, in a variety of contexts,both in vivo and in vitro. In general, to so modulate (e.g., increase ordecrease in a statistically significant manner) such a response, a cellis contacted with an agent that modulates DSP-11 activity, underconditions and for a time sufficient to permit modulation of DSP-11activity. Agents that modulate a cellular response may function in anyof a variety of ways. For example, an agent may modulate a pattern ofgene expression (i.e., may enhance or inhibit expression of a family ofgenes or genes that are expressed in a coordinated fashion). A varietyof hybridization and amplification techniques are available forevaluating patterns of gene expression. Alternatively, or in addition,an agent may effect apoptosis or necrosis of the cell, and/or maymodulate the functioning of the cell cycle within the cell. (See, e.g.,Ashkenazi et al., 1998 Science, 281:1305; Thornberry et al., 1998Science 281:1312; Evan et al., 1998 Science 281:1317; Adams et al., 1998Science 281:1322; and references cited therein.)

Cells treated as described above may exhibit standard characteristics ofcells having altered proliferation, differentiation or survivalproperties. In addition, such cells may (but need not) displayalterations (e.g., statistically significant increases or decreases) inother detectable properties, such as contact inhibition of cell growth,anchorage independent growth or altered intercellular adhesion. Suchproperties may be readily detected using techniques wit hwhich thosehaving ordinary skill in the art will be familiar.

THERAPEUTIC METHODS

One or more DSP-11 polypeptides, modulating agents (including any agentthat specifically binds a DSP-11, such as an antibody or fragmentthereof as provided herein) and/or polynucleotides encoding suchpolypeptides and/or modulating agents may also be used to modulateDSP-11 activity in a patient. As used herein, a “patient” may be anymammal, including a human, and may be afflicted with a conditionassociated with DSP-11 activity or may be free of detectable disease.Accordingly, the treatment may be of an existing disease or may beprophylactic. Conditions associated with DSP-11 activity include anydisorder associated with cell proliferation, including Duchenne musculardystrophy, cancer, graft-versus-host disease (GVHD), autoimmunediseases, allergy or other conditions in which immunosuppression may beinvolved, metabolic diseases, abnormal cell growth or proliferation andcell cycle abnormalities. Certain such disorders involve loss of normalMAP-kinase phosphatase activity, leading to uncontrolled cell growth.DSP-11 polypeptides, and polynucleotides encoding such polypeptides, canbe used to ameliorate such disorders.

For administration to a patient, one or more polypeptides,polynucleotides and/or modulating agents are generally formulated as apharmaceutical composition. A pharmaceutical composition may be asterile aqueous or non-aqueous solution, suspension or emulsion, whichadditionally comprises a physiologically acceptable carrier (i.e., anon-toxic material that does not interfere with the activity of theactive ingredient). Such compositions may be in the form of a solid,liquid or gas (aerosol). Alternatively, compositions of the presentinvention may be formulated as a lyophilizate or compounds may beencapsulated within liposomes using well known technology.Pharmaceutical compositions within the scope of the present inventionmay also contain other components, which may be biologically active orinactive. Such components include, but are not limited to, buffers(e.g., neutral buffered saline or phosphate buffered saline),carbohydrates (e.g., glucose, mannose, sucrose or dextrans), mannitol,proteins, polypeptides or amino acids such as glycine, antioxidants,chelating agents such as EDTA or glutathione, stabilizers, dyes,flavoring agents, and suspending agents and/or preservatives.

Any suitable carrier known to those of ordinary skill in the art may beemployed in the pharmaceutical compositions of the present invention.Carriers for therapeutic use are well known, and are described, forexample, in Remingtons Pharmaceutical Sciences, Mack Publishing Co. (A.R. Gennaro ed. 1985). In general, the type of carrier is selected basedon the mode of administration. Pharmaceutical compositions may beformulated for any appropriate manner of administration, including, forexample, topical, oral, nasal, intrathecal, rectal, vaginal, sublingualor parenteral administration, including subcutaneous, intravenous,intramuscular, intrasternal, intracavernous, intrameatal orintraurethral injection or infusion. For parenteral administration, thecarrier preferably comprises water, saline, alcohol, a fat, a wax or abuffer. For oral administration, any of the above carriers or a solidcarrier, such as mannitol, lactose, starch, magnesium stearate, sodiumsaccharine, talcum, cellulose, kaolin, glycerin, starch dextrins, sodiumalginate, carboxymethylcellulose, ethyl cellulose, glucose, sucroseand/or magnesium carbonate, may be employed.

A pharmaceutical composition (e.g., for oral administration or deliveryby injection) may be in the form of a liquid (e.g., an elixir, syrup,solution, emulsion or suspension). A liquid pharmaceutical compositionmay include, for example, one or more of the following: sterile diluentssuch as water for injection, saline solution, preferably physiologicalsaline, Ringer's solution, isotonic sodium chloride, fixed oils such assynthetic mono or diglycerides which may serve as the solvent orsuspending medium, polyethylene glycols, glycerin, propylene glycol orother solvents; antibacterial agents such as benzyl alcohol or methylparaben; antioxidants such as ascorbic acid or sodium bisulfite;chelating agents such as ethylenediaminetetraacetic acid; buffers suchas acetates, citrates or phosphates and agents for the adjustment oftonicity such as sodium chloride or dextrose. A parenteral preparationcan be enclosed in ampoules, disposable syringes or multiple dose vialsmade of glass or plastic. The use of physiological saline is preferred,and an injectable pharmaceutical composition is preferably sterile.

The compositions described herein may be formulated for sustainedrelease (i.e., a formulation such as a capsule or sponge that effects aslow release of compound following administration). Such compositionsmay generally be prepared using well known technology and administeredby, for example, oral, rectal or subcutaneous implantation, or byimplantation at the desired target site. Sustained-release formulationsmay contain an agent dispersed in a carrier matrix and/or containedwithin a reservoir surrounded by a rate controlling membrane. Carriersfor use within such formulations are biocompatible, and may also bebiodegradable; preferably the formulation provides a relatively constantlevel of active component release. The amount of active compoundcontained within a sustained release formulation depends upon the siteof implantation, the rate and expected duration of release and thenature of the condition to be treated or prevented.

For pharmaceutical compositions comprising a polynucleotide encoding aDSP-11 polypeptide and/or modulating agent (such that the polypeptideand/or modulating agent is generated in situ), the polynucleotide may bepresent within any of a variety of delivery systems known to those ofordinary skill in the art, including nucleic acid, and bacterial, viraland mammalian expression systems. Techniques for incorporating DNA intosuch expression systems are well known to those of ordinary skill in theart. The DNA may also be “naked,” as described, for example, in Ulmer etal., Science 259:1745-1749, 1993 and reviewed by Cohen, Science259:1691-1692, 1993. The uptake of naked DNA may be increased by coatingthe DNA onto biodegradable beads, which are efficiently transported intothe cells.

Within a pharmaceutical composition, a DSP-11 polypeptide,polynucleotide or modulating agent may be linked to any of a variety ofcompounds. For example, such an agent may be linked to a targetingmoiety (e.g., a monoclonal or polyclonal antibody, a protein or aliposome) that facilitates the delivery of the agent to the target site.As used herein, a “targeting moiety” may be any substance (such as acompound or cell) that, when linked to an agent enhances the transportof the agent to a target cell or tissue, thereby increasing the localconcentration of the agent. Targeting moieties include antibodies orfragments thereof, receptors, ligands and other molecules that bind tocells of, or in the vicinity of, the target tissue. An antibodytargeting agent may be an intact (whole) molecule, a fragment thereof,or a functional equivalent thereof. Examples of antibody fragments areF(ab′)₂, −Fab′, Fab and F[v] fragments, which may be produced byconventional methods or by genetic or protein engineering. Linkage isgenerally covalent and may be achieved by, for example, directcondensation or other reactions, or by way of bi- or multi-functionallinkers. Targeting moieties may be selected based on the cell(s) ortissue(s) toward which the agent is expected to exert a therapeuticbenefit.

Pharmaceutical compositions may be administered in a manner appropriateto the disease to be treated (or prevented). An appropriate dosage and asuitable duration and frequency of administration will be determined bysuch factors as the condition of the patient, the type and severity ofthe patient's disease, the particular form of the active ingredient andthe method of administration. In general, an appropriate dosage andtreatment regimen provides the agent(s) in an amount sufficient toprovide therapeutic and/or prophylactic benefit (e.g., an improvedclinical outcome, such as more frequent complete or partial remissions,or longer disease-free and/or overall survival). For prophylactic use, adose should be sufficient to prevent, delay the onset of or diminish theseverity of a disease associated with cell proliferation.

Optimal dosages may generally be determined using experimental modelsand/or clinical trials. In general, the amount of polypeptide present ina dose, or produced in situ by DNA present in a dose, ranges from about0.01 μg to about 100 μg per kg of host, typically from about 0.1 μg toabout 10 μg. The use of the minimum dosage that is sufficient to provideeffective therapy is usually preferred. Patients may generally bemonitored for therapeutic or prophylactic effectiveness using assayssuitable for the condition being treated or prevented, which will befamiliar to those having ordinary skill in the art. Suitable dose sizeswill vary with the size of the patient, but will typically range fromabout 10 mL to about 500 mL for 10-60 kg animal.

The following Examples are offered by way of illustration and not by wayof limitation.

EXAMPLES Example 1 CLONING AND SEQUENCING cDNA ENCODING DSP-11

This Example illustrates the cloning of a cDNA molecule encoding humanDSP-11.

A conserved sequence motif defining a novel homology domain ofdual-specificity phosphatases was identified as follows: Dualspecificity phosphatases belong to the larger family of protein tyrosinephosphatases (PTPs) that share a conserved catalytic domain containing acysteine residue situated N-terminal to a stretch of five variable aminoacids followed by an arginine residue (Fauman et al., Trends In Bioch.Sci. 21:413-417, 1996). DSPs typically contain a PTP active site motifbut lack sequence homology to PTPs in other regions (Jia, Biochem. andCell Biol. 75:17-26, 1997). There is, however, no reported consensussequence that is conserved among DSPs, nor is a consensus regionapparent from examination of the known DSP sequences such as thosereferred to above. To derive a longer consensus DSP amino acid sequencemotif that would be useful for the identification of new DSP familymembers, multiple known human dual-specificity phosphatases sequenceswere aligned and compared. From an alignment of eight amino acidsequences derived from eight particular human DSPs having MAP-kinasephosphatase activity (FIG. 3), a candidate conserved homology region wasidentified. This homology region consisted of a 24-amino acid peptidesequence, based on analysis of the DSP regions situated on either sideof, and including, the PTP active site signature motif. Thus, acandidate peptide having the sequence:

NGRVLVHCQAGISRSGTNILAYLM SEQ ID NO:4

was used to search the Expressed Sequence Tag database (Nat. Center forBiol. Information, www.ncbi.nlm.nih.gov/dbEST). The search employed analgorithm (tblastn) capable of reverse translation of the candidatepeptide with iterations allowing for genetic code degeneracy withindefault parameters. The search results identified the EST AA479435 as acandidate MAP-kinase phosphatase sequence. Additional tblastn searcheswith the EST AA479435 identified the following ESTs comprising candidatepartial carboxyterminal DSP-11 coding sequences: AI1363485, AI309010,AI341528, AI302179, AA863013, AA341644; these searches also identifiedthe uncharacterized (i.e., not an EST) partial cDNA fragment AF086553.The ESTs did not include a complete coding region of an expressed genesuch as a gene encoding a DSP-11 having MAP-kinase phosphatase activity,or any region encoding a PTP active site, nor were the sense strand andopen reading frame identified.

To obtain a full length coding region, human kidney cDNA (reversetranscribed from human kidney RNA) was screened in 5′ and 3′ RACE (rapidamplification of cDNA ends) reactions as described (Frohman et al.,Proc. Nat. Acad. Sci. USA 85:8998, 1988; Ohara et al., Proc. Nat. Acad.Sci. USA 86:5673, 1989; Loh et al., Science 243:217, 1989) using 5′/3′RACE kits (Clontech, Palo Alto, Calif.; Life Technologies, Inc.,Gaithersburg, Md.) according to the supplier's instructions. Sequenceinformation immediately adjacent to the conserved sequence motif of ESTAA479435 was used in the 5′ and 3′ RACE reactions with human kidneycDNA, using the following primers (SEQ ID NOS:5 to 7):

DSP11-GSP1: 5′-CGGGTCGTAGTCGTCGGATTTCAGCAA-3′ SEQ ID NO:5 DSP11-GSP2:5′-CCTCTCCCCGTGCGTTGGCCTCGT-3′ SEQ ID NO:6 DSP11-SP5 5′-CGC ACG GGG AGAGGC TGT-3′ SEQ ID NO:7

Sequences of the resulting RACE 5′ products indicated the presence of anopen reading frame, but the deduced translated sequences lacked aninitiating methionine. RACE 3′ products generated with the DSP-11-SP5primer (SEQ ID NO:7) and having an open reading frame included a stopcodon, indicating that a DSP-11 coding region 3′ terminus had beenidentified. To determine the DSP-11 coding region 5′ terminus, thededuced sequence was used to search the EST database as described aboveand additional ESTs, AA101787 and AA159216, were identified thatcorresponded to the 5′ RACE product derived sequence. To confirm theDSP-11 full-length coding sequence and to account for apparent minorsequence differences between these ESTs, the following primers for thefull length DSP-11 protein were designed to establish the coding regionfor the DSP-11 amino terminus:

DSP11EX5′: 5′-GAG GAA TAA TAA ATG ACC CGC TGT CCT GTG CCC TTT CCC AG-3′SEQ ID NO:8 DSP11EX3′: 5′-TTTCGTTCGCTGGTAGAACTGGAAGACTGCTTTC-3′ SEQ IDNO:9

PCR amplification from kidney cDNA templates using the primer pairDSP11EX5′ [SEQ ID NO:8] and DSP11-EX3′ [SEQ ID NO:9] yielded an ampliconhaving the predicted sequence, including sequences encoding initiatingmethionine of DSP-11 plus two base pairs 5′ to the ATG initiation codonat the 5′ end, and a sequence encoding C-terminal lysine but, by design,lacking the stop codon at the 3′ end. A cDNA (FIG. 1; SEQ ID NO:1)encoding a protein of 150 amino acids (FIG. 2; SEQ ID NO:2) was thusidentified as DSP-11. This sequence has significant homology to otherMAP-kinase phosphatases (FIG. 3). The identified cDNA contains the 450base pair coding region, as well as associated 5′ and 3′ untranslatedsequences (FIG. 1). The active site domain for DSP-11 was localized tothe region encoded by nucleotides beginning at position 273 of SEQ IDNO:1.

Semiquantitative RT-PCR analyses were performed. These analyses showeddetectable DSP-11 encoding mRNA in RNA sample from all human tissuesanalyzed, including brain, thymus, placenta, skeletal muscle, testes andadipose tissue, with apparently higher DSP-11 expression levels inkidney and liver.

Example 2 DSP-11 EXPRESSION IN HUMAN TISSUES

In this example, a DSP-11 encoding nucleic acid sequence is shown tohybridize to human polyA+ RNA from various tissue sources. Full lengthDSP-11 encoding cDNA (SEQ ID NO:1) was ³²P-labeled by the random primermethod as described in Ausubel et al. (1998 Current Protocols inMolecular Biology, Greene Publ. Assoc. Inc. & John Wiley & Sons, Inc.,Boston, Mass.) for use as a nucleic acid hybridization probe. The probewas hybridized to blots containing human polyA+ RNA derived frommultiple human tissues, normalized for the amount of detectable β-actinmRNA (FIG. 4, Cat. No. 7759-1; Clontech, Inc., Palo Alto, Calif.). Blotsunderwent prehybridization for 30 min at 68° C. in Express Hyb™ solution(Clontech), and then were hybridized with the labeled probe for 1 hourat 68° C. in Express Hyb™ solution. The blots were next washed for 40min at room temperature in 2×SSC, 0.05% SDS, followed by a second washfor 40 min at 50° C. in 0.1×SSC, 0.1% SDS. Blots were then exposed toHyperfilm MP™ autoradiographic film (Amersham Life Sciences, ArlingtonHts, Ill.) overnight. Results are shown in FIG. 4, in which the humantissue sources for the RNAs were as follows: Lane 1, He, heart; lane 2,Br, brain; lane 3, Pl, placenta; lane 4, Lu, lung; lane 5, Li, liver;lane 6, SM, skeletal muscle; lane 7, Ki, kidney; lane 8, Pa, pancreas.

Example 3 IDENTIFICATION OF A MURINE DSP-11 VARIANT

This example describes identification of a murine DSP-11 variant, basedon the DSP-11 sequence identified in Example 1. The full-length DSP-11encoding polynucleotide sequence (SEQ ID NO:1) was submitted to the ESTdatabase (Nat. Center for Biol. Information, www.ncbi.nlm.nih.gov/dbEST)as a search sequence, using the Advanced BLAST algorithm and dbestoptions with the organism field restricted to Mus musculus, and thefollowing two ESTs were obtained as best matches: AA023073 and AW258860.Alignment of these two EST sequences with each other and with SEQ IDNO:1 showed high homology between a portion of AA023073 and the DSP-11coding region of SEQ ID NO:1, while AW258860 exhibited high homologywith a large portion of the DSP-11 coding sequence of SEQ ID NO:1beginning with the N-terminal region, but lacked a polynucleotide regioncorresponding to the portion of SEQ ID NO:1 that encodes the DSP-11C-terminal region. AA023073 and AW258860 displayed nucleotide sequenceidentity over the region corresponding to DSP-11 encoding nucleotides1-316 of SEQ ID NO:1; 3′ to this position the sequence of AA023073 couldalso be readily aligned with SEQ ID NO:1 but lacked a single base paircorresponding to DSP-11 encoding nucleotide position 353 of SEQ ID NO:1and contained a C→G substitution in the coding strand at the nucleotideposition corresponding to DSP-11 encoding nucleotide 438 of SEQ ID NO:1,thereby generating downstream a premature stop codon regardless ofwhether correction was made for the frameshift. Proceeding in the 3′direction from the position corresponding to DSP-11 encoding nucleotide316 of SEQ ID NO:1, AW258860 diverged substantially.

Another EST identified in the database search described in this Examplewas W41278, the first nucleotide of wich could be aligned with thenucleotide at position 139 in the DSP-11 coding strand sequence o SEQ IDNO:1, to show essential identity with the portion of SEQ ID NO:1 thatencodes the C-terminal region of DSP-11, moving in the 3′ direction fromposition 139. W41278 lacked th C→G substitution that was present in theAA023073 coding strand at the nucleotide position corresponding to nt438 of SEQ ID NO:1, as described above. From the sequence alignments ofthe ESTs, the complete coding sequence for the murine DSP-11 variantthus became apparent to yield the full length nucleotide sequence shownin FIG. 5 (SEQ ID NQ:12 which encode the murine DSP-11 variantpolypeptide sequence shown in FIG. 6 (SEQ ID NO:13), wherein themismatches identified in AA023073 that generate premature stop codonshave been corrected according to the W41278 sequence.

To molecularly clone this murine DSP-11 variant, a polynucleotidecontaining the full length coding sequence is amplified from a murineplacenta cDNA library using standard PCR conditions (annealingtemperature of 72° C., 35 cycles) and the following primers:

mDSP-11-5′: 5′-ATG GGC GTG CAA CCC CCC AAC TTC TCC-3′ (SEQ ID NO:10)mDSP-11-3′: 5′-TCA TTT TGT TCG CTG GTA GAA CTG GAA GAC GGC C-3′ (SEQ IDNO:11)

From the foregoing, it will be appreciated that, although specificembodiments of the invention have been described herein for the purposeof illustration, various modifications may be made without deviatingfrom the spirit and scope of the invention. Accordingly, the presentinvention is not limited except as by the appended claims.

1. An isolated polypeptide comprising the sequence of DSP-11 recited inSEQ ID NO:2.
 2. A DSP-11 substrate trapping mutant polypeptide thatdiffers from the sequence recited in SEQ ID NO: 2 by a substitution atposition 65 or position 95 of SEQ ID NO: 2, such that the polypeptidebinds to a substrate with an affinity that is no substantiallydiminished relative to DSP-11, and such that the ability of thepolypeptide to dephosphorylate a substrate is reduced relative toDSP-11.
 3. An isolated polypeptide that is encoded by a polynucleotidewhich encodes a polypeptide capable of dephosphorylating an activatedMAP-kinase, said polynucleotide comprising a seq ence at least 80%identical to a polynucleotide that encodes a polypeptide comprising anamin acid sequence set forth in SEQ ID NO:2.
 4. An isolated polypeptidethat is encoded by a polynucleotide which encodes a polypeptide capableof dephosphorylating an activated MAP-kinase, said polynucleotidecomprising a seqence at least 90% identical to a polynucleotide thatencodes a polypeptide comprising an amin acid sequence set forth in SEQID NO:2.
 5. An isolated polypeptide that is encoded by a polynucleotidewherin the polypeptide capable of dephosphorylating an activatedMAP-kinase, said polypeptide comprising an amino acid sequence of SEQ IDNO:2, wherein an aspartic acid is located at position 65 and the peptides uence VGVHCALGFGRTGTMLACYLV (SEQ ID NO:3) is located at positions 91through 111 of SEQ ID NO:2, wherein said polynucleotide comprises asequence at least 80% identical o a polynucleotide that encodes apolypeptide comprising the amino acid sequence of SEQ ID NO:2.